HVAC School - For Techs, By Techs

In this short podcast episode, we talk through stack effect. We explain what it is and what sorts of comfort issues it can cause in a home. Most of us understand that hot air rises even though heat itself doesn't rise. The stack effect is precisely a version of that piece of common knowledge; hotter air is less dense than cooler air, so it floats above the cooler air. In hotter air, the molecules move a lot faster than they do in cooler air, so they can start to separate from each other, which reduces the overall air density. For the most part, we don't work pressurize air in HVAC work (not refrigerant), but we do change the temperature. The temperature changes cause the difference in air densities to emerge. If we're dealing with a furnace system in a two-story house or a home with high ceilings, we see that stack effect in action. When that hotter air rises and cooler air sinks, the hotter air makes way for a vacuum that draws colder air into the building. While that hot air rises, the colder air comes in under doors and through low cracks. Although the air that's coming out of the appliance is warm, it can't do much to heat the space before rising. The reverse stack effect can also happen. When you have poorly sealed can lights or cracks in the ceiling, the colder, denser air will sink and create negative pressure near the highest point of the room. When we have that negative pressure, hot air can get pulled in from the attic or other undesirable locations. In Florida, we have to worry quite a bit about the reverse stack effect, whereas the stack effect is more of a concern for colder climates. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jim Bergmann gives us a year-end review of all that is happening at MeasureQuick and his predictions for the future of app-based diagnosis. He also covers what's been going on with Redfish, BluFlame, BluVac, Supco, Testo, and Fieldpiece. Diagnostic tools only work if the buyers understand how to use them. When apps can assist the tool buyers and users with diagnosis, the tool manufacturers can focus more on improving the technology; they can leave the software and education to mobile applications. Implementing gas appliance diagnostic education has been a challenge for Jim and other app developers. However, they are attempting to take app-based gas appliance diagnosis to the next level. The goal of diagnostic apps is to educate technicians about tools and readings and to make diagnoses more comprehensive. From the start, one of MeasureQuick's major focuses has been accessibility and ease of use. A diagnostic app that gives technicians a seamless way to take readings, store data, and learn about their measurements should be easy to use, so Jim has put a lot of work into making a user-friendly app. So, the next step for MeasureQuick in terms of accessibility will likely be to allow users to share data for remote viewing. MeasureQuick has incorporated education on the basic refrigerant circuit, electrical components, gas appliances, and vacuum within the app. Soon, Jim would like MeasureQuick to expand into the refrigeration and geothermal sides of the HVAC/R world; he'd also like to implement project notes. Jim and Bryan also discuss: Monetizing diagnostic apps Tying tools into diagnostic software Wireless range and BlueTooth considerations Working with programmers How much might I invest in an app-based diagnosis app? Third-party quality control Future-proofing Project or process-based functions Integration Electronic accessibility and pricing Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

What is the difference between accuracy, precision, and resolution? In today's short podcast, Jim Bergmann explains the differences and why they matter. People commonly confuse accuracy and precision. Accuracy refers to how close a measurement is to the correct value, but precision refers to the consistency of values. For example, you can get several infrared thermometers to measure the difference between circuit breakers, and the thermometer readings all come out close to the same value. They aren't necessarily accurate, but they are precise. In cases where we use a voltmeter to measure for the presence of voltage, we don't need a high degree of accuracy. However, when we want to measure exact voltage values, we want to make sure our tools are accurate. Sometimes, voltage that is too low can cause issues with the circuit boards. Resolution refers to the smallest possible amount of change you can detect. For example, one voltmeter may measure to the nearest whole volt, and another may measure to the nearest tenth of a volt. The resolution is higher on the latter voltmeter, as it detects a smaller change than the first voltmeter. Some tools measure with a high resolution, but the increased resolution may compromise the accuracy. For example, if a manometer reads into the Pascals range, it may only have a tolerance of +/- 5 Pascals, which leaves room for inaccuracy. However, again, accuracy is not always the most important value. Sometimes, resolution and precision are more important than accuracy. After all, in the words of Jim Bergmann, it's pretty difficult to measure feet with your car odometer. One common example where precision and resolution are more important than accuracy is when techs try to measure microns with analog gauges. The accuracy means nothing when the precision and resolution are poor. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

John guides us through all aspects of ventilation and system design. He gives us a review of point ventilation, ASHRAE 62.2, whole-home strategies, and much more. Nowadays, construction protocols instruct builders to make houses tighter than the builders of the past. The goal of building tighter homes is to give us more control over the temperature, quality, and energy impact of the outside air we bring into our homes. Common sources of ventilation are local exhaust systems, including bath fans and kitchens. However, in tighter constructions, there is a greater need for whole-home strategies to bring in outside air and dilute indoor-generated pollutants. Some of those pollutants include VOCs, odors, and moisture. We must think about how to introduce that outside air into the home and how that outdoor air will impact heat loads, moisture levels, and air quality inside the home. When we select equipment for airflow, we need to think about constant vs. intermittent flow. In humid climates, you also need to take extra steps to prevent moist outdoor air from leading to excess condensation in the home. Ventilation equipment either delivers outdoor air to each room or mixes that outdoor air with the return air. Try to ensure that the space temperature doesn't drop below the dew point, which can be a challenge in humid climates. Ventilating dehumidification is a promising solution for HVAC system replacements and new constructions in humid climates. In cold, tight homes, ventilating dehumidification can keep a home dry enough to keep occupants comfortable in the winter. John and Bryan also discuss: Why do people want energy efficiency? "Passive house" and airtightness standards Mixing air and filtration Carbon dioxide (CO2) ERVs vs. HRVs for balanced ventilation Fan cycler systems Duct installation quality Dedicated make-up air Fireplaces and gas appliances under negative pressure Learn more about Think Little, John's company, at think-little.com/. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bill and Bryan discuss gas and combustion tools. These tools include manometers, combustible gas detectors, personal CO detectors, draft gauges, and combustion analyzers. Manometers measure gas pressure, and they require calibration but are usually quite accurate. Before using a manometer as a diagnostic tool effectively, you must understand your targets and resolution. Some digital manometers come with BlueTooth technology, so you can log, convert, and store your data on mobile devices. Gas leak detectors are relatively inexpensive tools. These should NOT be confused with combustion analyzers, which are different tools altogether. You usually cannot calibrate these tools. When using a gas leak detector, the leak detection process on gas pipes is similar to the electronic leak detection process on straight-cool A/C units. Draft gauges measure very fine pressure differentials in the combustion air zone. These may use flappers or vanes to give you data about the direction and amount of draft. Most importantly, you want to ensure that you have no backdraft. These tools take very fine measurements, so they have high resolution. Because of their high resolution, they require frequent calibration to stay accurate. Personal (or ambient) CO monitors are also important gas and combustion tools. Carbon monoxide (CO) is odorless and colorless, and it can be deadly. To avoid CO poisoning, use one of these monitors to remain aware of the CO content in your space. Combustion analysis has evolved a lot over the years. Today, we perform combustion analysis with a single tool. When combustion occurs, a chemical reaction occurs. Combustion analyzers determine what happens post-combustion by taking temperature and oxygen readings. However, they also account for the presence of CO, which indicates incomplete combustion. Bill and Bryan also discuss: Analog and Magnehelic manometers BPI-1200 Precision CO monitor upkeep/disposal Perfect combustion AHRI-1260 Nitric oxide filters Choosing tools Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan speed-talks through all the basics of heat pumps and how they function. Heat pumps are not physical pumps or components on an A/C system. A heat pump is an HVAC unit that is also capable of heating a home by reversing the refrigeration cycle. When that reversal happens, the traditional indoor "evaporator" coil acts as a condenser that rejects heat in the home. As such, the traditional outdoor "condenser" acts as an evaporator that absorbs heat from the outdoors so long as the refrigerant is colder than the outside. Due to how they function, heat pumps are more common in warmer climates. The heat pump's reversal happens on the reversing valve, which diverts refrigerant right before the compressor. A solenoid shifts the valve when you enter heat mode from cool mode (or vice versa), and that's how refrigerant gets diverted. These just slide back and forth, and they are pretty reliable; they don't typically malfunction. Before a reversing valve can work, the system must be ON; the valve cannot shift if the unit is OFF. Heat pumps typically have two metering devices, one by the indoor unit (cool mode) and one by the outdoor unit (heat mode). A check valve controls the flow of refrigerant to the correct metering device. Heat pump systems may also often have suction accumulators and crankcase heaters to help prevent oil loss and flooded starts in the compressor. The defrost controls for heat pumps typically have a timer and defrost sensors. We also discuss: Issues with heat mode TXVs Checking the charge on a heat pump Defrost sensor types and operation Auxiliary heat Economic balance point Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jason from ESCO and Cengage comes on to talk about the varying landscape of EPA 608 regulations with what you need to know for now (circa 2018). The EPA has proposed to roll back some regulations regarding HFC refrigerants, including leak rate and leak repair mandates. There are also questions about the regulation of refrigerants that do NOT have ozone-depleting substances, not just HFCs. This choice reinterprets language within the guidelines put forth in 2016 and the Clean Air Act. However, this choice completely disregards global warming potential and limits regulations of refrigerants with global warming potential but no ozone-depleting potential. EPA 608 still prevents the venting of non-natural refrigerants, but the proposed changes aim to clarify the language in those regulations. EPA 608 Subpart F can potentially be rescinded entirely. That action could muddy the language as to what constitutes venting. HVAC businesses can also suffer, as technician certification may no longer be a requirement for purchasing refrigerants. (Not to mention, homeowners can ignorantly engage in harmful practices, like cross-contaminating refrigerants and venting. Substance abuse is also much more accessible if non-HVAC techs purchase refrigerant to huff it.) The USA is actually well behind other industrialized countries when it comes to refrigerant usage. We're one of the only industrialized countries that have yet to really move forward from HFCs. So, rolling back HFC regulations may be a step back for environmental initiatives, refrigerant innovation, and even the refrigerant reclamation job market in the USA. Jason and Bryan also discuss: EPA exam changes Individual state regulations and certifications Who benefits from these changes? Comparisons to other toxic chemicals Air quality, pollution, and resource exploitation Refrigerant recovery and mixing How will this change affect the job market? How will this change affect education and writing? Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan shares his experience as an entrepreneur and his tips for anyone who wants to run and grow a successful business. When growing a business, the best thing you can do is listen to others who have started a business. It's especially useful to listen to those who have already "made it" in the business world. Growing a business requires you to stay focused. While you may have to work in your business, you also want to make time to work on the strategic parts of your business. Make goals, hire good people, and make sure your business has all the right people and tools to help it grow. Know your hirees' motives, and it's also important that the people in your personal life support you. Your business will also grow most effectively if you can keep your emotions under control. On a financial level, you need to have a good grasp of your personal finances before tackling business finances. Make wise decisions, and don't make excuses to spend money on things your business doesn't actually need. One of our main business tips is that it's best to avoid dumping your money into things you don't understand. Marketing is something that a lot of HVAC businesspeople don't understand and may not actually need. So, keep your investments limited to things you understand early on. Networking is a critical element of business. Your business needs to develop relationships with people you can trust. Trust-based relationships help foster an appreciation between your customers and your business. Appreciation for employees is another element of this. When everyone is aware of the value of your relationships, your business can grow with the right people within the company and the right people paying for your services. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In our first ever ask-me-anything (AMA) podcast, we talk about the trade as a whole and answer random questions about Kalos and myself. Some people ask me if I'd encourage my children to get into HVAC/R. In my opinion, the trade offers plenty of good opportunities and room for growth. So, I will definitely encourage my children to get into the trades, but I will not pressure them into it. I think more of us should encourage our children to consider a career in the trades and understand the benefits of those careers. I'd even say that I'd choose this career path again if I were allowed to restart my life and take a new career path. I'm optimistic about the future of the trade. The pay and opportunities are better than they've ever been before, and we have chances to attract young people to the trade. This trade is one of impact, and impact is becoming increasingly important to young people. One of the main issues we need to address in our trade is unprofessionalism. From bad practices to blatant prejudice, we need to be professional, proud of the work we do, and fair to everyone. We also discuss: Which piece of equipment I identify with Sleep schedules for people who work on many things at once Providing tools and tool stipends HVAC company finances and profit Tech traits across trades The separation between commercial and residential HVAC Unprofessionalism in the trade Taking time to read and do research Time management and discipline Mechanical diagnosticians vs. sales techs What inspired me to get into HVAC Innovation, marketing, and corporate culture among manufacturers Onboarding and training green techs Thanks to everyone who asked questions in this AMA. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

When we replace equipment, we sometimes wonder if the old unit was undersized. Here are some things to consider before replacing that old A/C with a bigger one. When we do load calculations, we figure out how much heat to remove or add to a home based on the building's design. We need to account for how much heat is entering or leaving a building and heat gains on the inside of a space. Heat gains can come from human body heat or electronics running, and heat losses are quite rare. Those factors are perhaps even more important for correct sizing than mere square footage. In general, I don't recommend putting a bigger unit in. Focus on getting the equipment to work properly before considering an upsize, as the improper cooling could be caused by a mechanical issue and not an undersized unit. If you want to dig deeper and consider upsizing a unit, you have to consider a few things. First of all, you want to look at the sensible and latent loads. Is the unit too small on the sensible or latent side? In either case, you can adjust the blower to try to address these first. If humidity is the issue, you do NOT want to oversize the unit. Is leakage a factor? Check the integrity of the duct system and if you have cracks, can lights, or other sources of leakage. How's our ventilation? Attic ventilation is also a huge factor that will determine how well an A/C unit works. We also discuss: Shade and impact on radiant gains Ductwork, wire, and copper pipe sizing Heat load reduction (lighting, ventilation, etc.) Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

What is the difference between r-value and u-factor? Why should we care about the differences? In this short podcast, we'll explain what those differences between the two are and why you should care. R-value and u-factor are actually pretty close to the same thing; they are inverse coefficients of the same phenomenon. R-value is the resistance to heat energy moving through conductance. R-value is not concerned with radiant gains, such as the sun's UV rays passing through a window; the heat gains occur strictly through conduction, molecule-to-molecule, like heat passing from the wall insulation to the actual wall upon contact. In terms of insulation, a higher r-value is desirable, Inversely, we like to see a lower u-factor. The u-value is the coefficient of heat transfer. So, the r-value's resistance to heat acts directly against the heat transfer of the u-factor. You can convert the u-factor to r-value by dividing the u-factor into 1 (1/u-factor). Similarly, you can get your u-factor from your r-value by dividing the r-value into 1 (1/r-value). We use these values in load calculations and plug them into Manual J programs. We figure out our BTUs per hour in an equation where we multiply the square feet by the u-factor and the delta t. So, our insulation plays into equipment sizing. Some products also have a rated u-factor. You also need to average out the u-factors if you use multiple materials. (Note: sometimes, manufacturer u-factor ratings are not entirely accurate.) Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

This episode is very exciting to me because we get to have Dr. Allison Bailes on the show. Today, he shares his knowledge about friction rate and duct design. Allison got his start teaching college-level physics before getting into the building design industry. If you have a forced-air system that blows heated or cooled air through a duct system, that blower creates a pressure difference. Some of the pressure is used up on the filter, registers, and dampers, so you will see pressure drops. Anything left over is the available static pressure, which pushes air through the ducts. When you do a duct design, you must account for pressure drops and your blower's static pressure rating. When designing a duct system, you want to minimize friction as much as possible. Counterintuitively, you want a high friction rate. Friction rate refers to the availability of static pressure compared to friction provided by the effective length, not the total amount of friction. Fittings significantly impact your total effective length. By extension, fittings can have a major impact on friction. In flex duct designs, the turns add additional resistance. Oversizing often happens due to poor load calculation. While you increase capacity with an oversized system, there are plenty of drawbacks. The capacity will rarely match the load, you may spend too much on the equipment, have ineffective dehumidification, and you will deal with short cycles, which lead to comfort problems. Allison and Bryan also discuss: Home energy ratings Equivalent length and total effective length Flex duct design Seasonal runtime Surface area challenges Unconditioned spaces Filtration To find out more about everything Dr. Bailes has to say about building performance and duct design, visit his site at: https://www.energyvanguard.com/blog Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Rusty Walker with Hill-Phoenix comes on and talks about CO2 triple and critical points. He also covers some best practices for refrigeration techs working with CO2. The triple point is the temperature and pressure at which a substance can exist in all three phases of matter. CO2 has a very high triple point, and CO2 refrigeration equipment can reach its triple point during operation, unlike most other refrigerants. Solid CO2 is dry ice, and it sublimates by becoming a gas and bypassing the liquid CO2 phase under low-pressure conditions. Therefore, the relatively high pressure applied in a CO2 refrigeration system keeps the refrigerant in a liquid state. We want to avoid reaching the triple point because solids can cause restrictions. The critical point is the point at which a substance becomes a supercritical fluid and loses its pressure-temperature relationship due to densities equalizing. CO2 has a low critical point, only 87 degrees Fahrenheit. So, CO2 refrigeration systems will have supercritical or transcritical CO2 in their systems. You cannot calculate superheat under these circumstances, and you cannot condense supercritical fluid. So, you need to send the supercritical fluid through a gas cooler to reduce the temperature before it can change state. Critical and triple points are important to keep in mind when working on a CO2 system. You want to control pressure to steer clear of the triple point and understand the necessity of gas cooling when dealing with supercritical fluid. Remember: all of the basic laws of thermodynamics still apply. Rusty and Bryan also discuss: CO2 leak detection Bars and pressure conversions Supercritical fluid as a solvent Avoiding triple point on a service call Recommended equipment and practices for working on CO2 systems Vacuum Booster system piping and brazing Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, we cover what you need to consider before you solder or braze any type of joint in HVAC/R work. We want to give special thanks to Solderweld; you can learn more about their products at solderweld.us. When you braze or solder anything, you need to know your base metal. The base metal's temperature and composition will determine which type of flux you will use. For example, if you are working with steel, you can't use fluxing agents with phosphorus. Instead, you will need to use high silver rods and a separate flux. Copper rods with phosphorus don't require a separate flux. The main difference between brazing and soldering is the temperature. When you work with temperatures above 840 degrees Fahrenheit, you're brazing. Anything below 840 degrees counts as soldering. In both cases, you use an alloy that differs from the base metals. Copper is highly conductive and is one of the most common metals we use for brazing and soldering. So, it is pretty easy to draw the alloy into a copper-to-copper joint because the copper heats easily and evenly. Steel is nowhere near as conductive as copper, so it can be challenging to work with because the heat localizes. So, on copper-to-steel joints, you need to understand the different behaviors of the metals. It's also a good idea to know the melting point of your base metals to prevent overheating. As we heat base metals, they change color. When those metals get to a cherry red, that's a great range for brazing; don't let the temperature rise or fall much below that. We also discuss: Soft solder Metal expansion and contraction Copper-to-aluminum brazing challenges and practices Flux usage and best practices Alloy-Sol and bonding Preventing leaks Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Eric Mele is back on the podcast. This time, we cover hot gas as a reheat dehumidification strategy with all of the broad strokes you should be aware of. One common dehumidification strategy is the hot gas bypass; this strategy allows you to operate under low load. Hot gas reheat is when you add discharge heat back to the conditioned space. When you use reheat for dehumidification, you cool for the purpose of dehumidification and then add sensible heat to remove moisture on the coil. So, you don't overcool the space to an uncomfortable level. Hot gas reheat uses waste heat from the equipment to remove moisture. Using waste heat is not a very efficient process, but it is better than using electricity or fuel to provide a heat source. Common systems that use this reheat system are 100% outside air units and humidity-control applications. Systems that use hot gas reheat can divert refrigerant to a reheat coil or use a dedicated reheat circuit. No matter which strategy the equipment uses, the reheat always happens AFTER the evaporator coil. Common issues with these reheat systems deal with the modulating valves. These valves can get stuck or end up in a different position than their controls say. You must confirm that the valves are in position. When working with these valves, you may work with DC controls, so that's something to keep in mind if you primarily work with AC circuits/controls. DC-signal sensors can also malfunction, so you have to check your outputs and can usually find a sensor-related problem quite easily. We also discuss: Overcooling to dehumidify Fresh air requirements and equipment Solenoids Expansion line Technician vs. manufacturer training Confirming valve position Stepper motors Tools for circuits Checking the refrigerant charge Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan covers three things you can do to level up and make you a much better tech tomorrow. Everyone will notice your improvement. Also, no matter what level you're on, you can become even better by remembering the following three tips: 1. Use a full-system diagnostic process. Every application should have a full-system diagnostic process, whether you're working on a residential ductless mini-split, a commercial chiller, or a walk-in refrigerator. Instead of focusing just on the primary problem, you'll be much more effective if you assess the entire system. You can also adopt a wide-narrow-wide approach to diagnosis where you start by examining the entire system (for example, look for oil and check the filter). Then, you focus on the main problem at hand and fix it. Before you leave a job, test the equipment and check it over once again to make sure that everything is working as it should. 2. Communicate better. In the commercial sphere, it's a good idea to write up equipment reports that customers can use to help them make informed choices about their equipment. For residential customers, communication is about courtesy. Send a text to let them know you're en route or send a follow-up email. When it comes to dispatch and leadership within your organization, communicate useful and helpful information for them. Report common things that you see in the field so that they can improve at their jobs. 3. Have a closing conversation with every customer. Before you leave a site, check in with your customer to make sure that there's nothing you or your company can do better. When you have these conversations, you show that you care and give the customers an opportunity to provide feedback. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Jim Bergmann does a deep dive into combustion analysis. He covers everything you need to know to keep a furnace running safely and efficiently. When you go into a home, one of the first things you should do is perform an ambient CO test to check how much carbon monoxide is in the home. Combustion analyzers can typically measure CO, or you could use a dedicated CO meter. When it comes to checking for spillage, you'll want to make sure you check anything that is connected to an atmospheric draft appliance; these appliances, including water heaters, can create a pathway for CO. First, you want to make sure everything is working properly before the combustion analysis. Set the fuel pressure according to the manufacturer's specs. Then, you go outside and clock the meter. When you do that, you merely verify that you have the correct gas input to the appliance; figure out how long it takes the one-foot dial to do a single revolution. After you verify the fuel and air, you want to see if you have an adequate amount of draft. Then, you set your temperature rise and verify that your CAZ zone is within the allowable limits. When we do a combustion analysis, we measure the efficiency of the combustion process, not the overall furnace efficiency (AFUE). Combustion analyzers also help us account for stack losses. When doing the test, you must measure undiluted flue gas and take readings on fuel pressure, excess air, and stack temperature. Jim and Bryan also discuss: Fuel pressure and fuel orifice sizing Fuel heat content Excess air and condensing Carbon monoxide thresholds Stand-by losses Contaminants Temperature rise ranges Net vs. gross stack temperature Combustion efficiency Duct leakage Positive vs. negative pressure exhaust Cracked heat exchangers What to do when CO levels are high AccuTools Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

This short podcast episode is about a simplified way to explain the basic refrigerant circuit to new techs. By explaining a component as an absorber, rejector, increaser, or dropper, you may help lock in the basic idea of absorbing and rejecting heat. The goal of refrigeration is to remove heat from a place. Whether that place is a grocery case or a house, we're moving heat. The overall function is pretty straightforward, but the components can get a little bit complicated. At Kalos, we've found that HVAC/R apprentices tend to grasp the refrigerant circuit better when they can refer to the components by their functions. We move heat with a combination of heat absorption and rejection and pressure rises and drops. For example, the compressor is the "pressure increaser," and the metering device is the "pressure dropper." Likewise, the evaporator is the "heat absorber," and the condenser is the "heat rejector." When we understand that higher energy goes to lower energy, we can understand that the cold refrigerant inside the evaporator acts as a heat absorber. The evaporator coil is lower than the indoor temperature; it can do its job as a heat absorber even in relatively cool spaces. In air conditioning, we try to maximize efficiency by creating the proper temperature inside the evaporator (heat absorber). In many places, that temperature is about 35 degrees (F) below the indoor dry-bulb temperature. Explaining the component in this way encourages technicians to check the space of the temperature and relate it to the evaporator temperature. The condenser is a heat rejector; it performs the opposite function of the evaporator. So, the outdoor temperature must be lower than the condenser (heat rejector) temperature. Then and only then can the condenser reject its heat to a cooler location. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this first part of the two-part combustion analysis series, Jim Bergmann covers CAZ testing or worst-case draft pressure testing in detail. He also explains why it matters to techs and customers. Once again, MeasureQuick will come in handy if you do CAZ testing in the field; Jim Bergmann is working on automating the testing process in his app. CAZ (combustion air zone) testing will benefit the customer in both safety and efficiency. A proper CAZ test will also likely increase the furnace system's longevity. This test identifies if there is a high potential for flue gas spillage. We want to check if the appliance is installed in a space where it can easily and safely vent combustion gases. Other appliances can potentially give off exhaust, and they may impede a combustion appliance's ability to vent properly. Worst-case draft pressure testing is a way of making sure that we have enough combustion air in a room for an appliance to operate safely. Some sealed combustion appliances can potentially suffer negative impacts of depressurization, which is dangerous despite the sealed combustion. First, you want to measure the CAZ pressure with respect to the outdoors. Then, you turn the air handler on and measure that pressure again to identify possible duct leakage. After that, you close the interior doors and measure the CAZ again. Redo all three of these steps to produce the highest negative pressure. You can measure your pressures with a good manometer or the draft gauge on your combustion analyzer; ideally, your tool's resolution will read tenths of Pascals. Jim and Bryan also discuss: Pressurization and pathways Radiant heaters and other appliances Disconnected supply Sealed and unsealed base pans Exhaust pipe ventilation Temperature-draft relationship Water heaters Resolution, accuracy, and precision Measurement tools Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, we talk about the commissioning mindset and what it REALLY takes to set up and commission a new system properly. We commonly check airflow and the refrigerant charge during commissioning. There is a difference between mere startup and commissioning. When you commission a system, you ensure that it is working according to design. Think about how the system lines up with the manufacturer's specs and how appropriately it fits its application. In Florida, our designs typically maximize latent heat removal, so we want our systems to run optimally by those standards. We have to check sensible and latent capacity to avoid short-cycling and maximize customer comfort. When comparing your equipment operation to the manufacturer's specs, you'll want to check the charge. You can check the suction pressure, outlet air temperature, and weigh in the charge with a proper scale. You should test the system to make sure that you don't have any leaks from the factory and that Schraders aren't causing any leaks. Ductless units can be tricky, as there may seem to be little to check. However, you can certainly weigh in the charge and check your pressures to make sure that the unit is running well. You can even check the ductless system's delivered capacity as part of the commissioning process. Communication with your installers is key. Tell the installers what your targets are so that they can make sure that the system delivers on the contractor's promises. Show your installers how to take the measurements so that they can confirm the operation. Other procedures that are vital to the commissioning mindset include balancing the ventilation and ensuring that air moves through the supply and return vents correctly. The goal of commissioning is to make sure we deliver on our promises. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, Rusty Walker from Hill Phoenix talks us through the three most common types of market CO2 systems and how they work: secondary, cascade, and booster. Carbon dioxide (CO2) is one of the oldest refrigerants; it is a natural refrigerant that came about when toxic refrigerants like ammonia were common. In the 1980s, we began to rediscover the benefits of CO2 in market refrigeration, including its high latent heat capacity, low costs, and low global warming potential. Secondary systems use an HFO or HFC on top, which acts as the primary system and helps discharge heat. These systems have large receivers with both liquid and vapor CO2, and they resemble glycol systems quite a bit. The actual CO2 side of the system moves a lot more heat than the primary system alone; the CO2 side absorbs heat from open cases on the sales floor. Cascade systems are two complete refrigeration systems tied into each other. Like secondary systems, these may use an HFC or HFO with the CO2 system. A heat exchanger exists between the two systems and serves as the evaporator for the upper cascade or the condenser for the lower cascade. Booster systems have an upper side and lower side. These may have multiple medium-temp and low-temp compressors. They also have a high-pressure control valve. That controller looks at drop leg temperature and pressure to regulate subcooling. These systems also have a flash gas bypass valve that discharges into the receiver or the medium-temp suction line. Rusty and Bryan also discuss: CO2 and ammonia Triple point Supercritical fluid Latent heat benefits Metering devices Thermal siphon Heat exchangers and pressure drop Upper vs. lower cascades CO2 pressures Compression ratio Subcritical and supercritical modes Adiabatic operation Climates You can also contact Rusty by email at [email protected]. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Can you really trust that temperature reading? In this short podcast episode, we talk about some common mistakes techs make when making temperature measurements and what to do about it. Many heat pumps use heat strips as a source of auxiliary heat. However, it takes some time for the heat strips to integrate with the air. So, your superheat, subcooling, and pressures will look fine on a system that isn't cooling well enough. When you take air temperature measurements in the ductwork, try to get as close to the center of the duct as possible or take a measurement farther down in the duct. Even so, you need to be careful with measurements in the center of the duct on gas furnace systems because radiant heat can give you an incorrect reading. You can also measure a few different points and average them out. On gas furnaces with a coil on top, the coil can be in visual contact with your temperature probe. In those cases, the coil will absorb some of the heat from your probe via radiant heat transfer, so you could end up with a lower reading. Not accounting for small sources of heat transfer is one of the most common temperature mistakes that techs can make. When measuring outdoor temperatures, you want to avoid using your probes in the sun. The sun can add radiant heat to your readings when you calculate CTOA, and you will get a high reading. Radiant heat gains also apply when you're working very close to hot, active pool heaters. The thermostat should also avoid being exposed to very high or low temperatures for maximum accuracy. We also discuss: Radiant heat gains Air mixing Line temperature clamps and copper cleanliness Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

James Bowman returns to the podcast to talk about analog vs. digital manifolds. He also explains why both of them may still have a place in the industry. Pricing is a key difference between analog and digital manifolds. Analog manifolds tend to be less expensive and will suffice just fine for techs who don't require readings with a lot of detail. While digital manifolds will be more expensive, they can also give you more precise, detailed readings. So, digital manifolds have a slight leg-up in terms of resolution as well; these manifolds are generally better for critical-charge or MicroChannel systems. Learning to take readings on analog manifolds early on may be advantageous for young or inexperienced techs. You learn more about superheat, subcooling, and interpreting readings when you start off with an analog gauge manifold. The process of taking readings on digital gauges is automated; therefore, digital gauges are less effective as learning tools. If you want to recover refrigerant, you might be better off using an analog manifold. These are less expensive and may be better equipped to deal with the nasty contaminants inside a system. Digital manifolds are more expensive and should not be exposed to contamination if you want them to last a long time. We often use accuracy and resolution interchangeably, but accuracy refers to the correctness of a reading. Resolution refers to the scale of the measurement. Digital manifolds usually have advantages in both of these areas, as they can usually take finer readings. James and Bryan also discuss: Critically charged systems Charging and recovery Hoses Ductless systems Technological and practical changes in our industry's future Using probes to take readings Single-port manifolds Applications where accuracy is most important Causes of inaccuracy Calibrating probes and other tools Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, we share some quick tips about keeping panels and insulation in place to avoid a costly screwup. Often, technicians will use an impact driver too aggressively. If you feel it begin to clutch, that means that the driver is actually impacting, and that means you're going too far. When that happens, you can strip out the screws, which can be a serious problem on larger equipment. On RTUs and other large commercial equipment, panels can fall off if you strip out those screws, which can be a costly screwup. So, don't strip out screws. Even if you need to put the screws in by hand or with a regular driver instead of with an impact driver, you'll see better long-term results. On normal drivers, you can also set the clutch so that the driver stops before it can strip out the screw threads. When panels fall off, the insulation can encounter issues as well. If the insulation peels off, please put it back on. Don't be afraid to use a little bit of spray glue to help mount that insulation to the inside of the panel. After using spray glue, you can finish mounting the insulation with some butyl tape on the edges, which has a heavy-duty adhesive and should last a long time. (Silver tape is okay, but it isn't nearly as strong as butyl tape.) When panels come off due to screws stripping out, they can blow away in extreme weather. In Florida, we have hurricanes in the summer and fall, so flying panels should be prevented at all costs. In some cases, you can even use a slightly larger screw to replace a missing screw if need be. Self-tappers also aren't the best screws you can use. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

John Pastorello, the HVAC chemist, comes on the podcast and discusses refrigerant additives such as acid inhibitors, oil enhancers, dyes, and leak sealants with his knowledge and some things to consider. Acid neutralizers are refrigerant additives. Oil works best in a slightly acidic environment, and these additives can change the pH of the system. If the pH becomes neutral or alkaline (basic), then the system will not operate as it should. Acid scavengers won't change your pH, but they are usually alcohol-based, which may attack aluminum in your system and make your windings brittle. Instead of relying on acid-reducing refrigerant additives, the best solution is to use and responsibly replace suction driers. Corrosion inhibitors are also refrigerant additives. OEMs sometimes use these on their own equipment or recommend the usage of corrosion inhibitors. However, these can come with their own set of impurities. These impurities can be even more detrimental if the products come from a foreign market. Solvent-type products assist oil return by reducing the oil viscosity. However, these solvents can cause the oil to foam and can quiet your compressor down. These foaming agents have no positive effects on your system; the compressor may run more quietly, but solvents have no effect on the amperage. Leak sealants are other additives. These started in the automotive industry, and manufacturers would void warranties on cars that had leak sealants in their systems. Leak sealants introduce solid particles into your system to patch up a leak. However, we can't actually repair leaks by patching them with fine solids. John and Bryan also discuss: Marketing tactics Additive testing Solutions for excessively acidic systems Oil sample analysis and testing for burnouts Suction drier usage and pressure drops Diluting corrosion inhibitors Non-polymer leak sealants Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Many technicians use hard or soft copper without thinking about which application is best for which. In this short podcast, Bryan talks about where to use each. He also covers some hanging and strapping strategies. Residential service technicians typically work with soft copper. Conversely, commercial techs are probably much familiar with the hard variety. Both hard and soft types are good for specific applications. If you need to work the copper, then the soft type is best for that. You can bend it by hand or with a bender without too much trouble, and it is ideal for flaring and swaging. However, it does not hang well and is not very structurally sound. If you need to hang copper through an attic or light commercial space, then you're really better off with the hard type. The soft kind also doesn't look quite as nice as its hard counterpart when you use it to feed several condensers with a line set. Hard copper is straight, rigid, and holds up much better than the soft kind when it must be strapped, and it sometimes comes with rubber plugs. Strapping is not a practice that we commonly think about in residential HVAC, but we still need to strap our piping appropriately. We can use Unistrut and clamps to strap our piping correctly. You can bend, swage, and flare hard copper, but you must heat it before you work it; the hard variety can take a lot more abuse than soft copper and is much more durable. You also probably can't transport this type of copper in a van easily, as it can come in very long segments. Check out Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

Kevan Mayer with NAVAC comes on and talks all about flaring best practices step by step. From cutting to reaming to torque wrenches, we cover how to make a flare from start to finish. The goal of making a good flare is to reduce leaks as much as possible, especially on ductless units and in commercial HVAC/R. When you make a flare, you have to make sure the depth is correct and consistent, especially on R-410a systems. NAVAC makes various flaring tools, including fast battery-powered ones, that can help you get a consistent depth on your flares. You can learn more about some of their flaring tools HERE. You start off making flares by cutting your tubing. Make sure you have a clean, square cut. Using a sharp tool cutter is the best way to make sure that you get that clean cut. Tighten your tool down in increments. Cleaner cuts make deburring/reaming easier. Assembly lubricants like Nylog and oil are excellent products to help you make a flare if used correctly. You don't want to let the oil or synthetic lubricants drip into the tube. Only use a little bit of these products, as too much Nylog on the threads can also change your torque spec. You can also put these lubricants on the cone of your flare tool. When assembling a flare, make sure that you follow the manufacturer's specs regarding height and flare nuts. Be mindful of the torque you apply during the assembly. Use a backing wrench and torque wrench for assembly. We also discuss: Reaming/deburring practices Differences in line sets with different refrigerants Flares in residential and commercial HVAC Flare gauges Torque specs and torque wrench usage Pressure considerations Leakage, pressure testing, and decay testing Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In today's podcast, Eric Mele and Bryan talk about chilled water air handlers, their valve configurations, and some key things to look out for. In a chilled water system, we don't have the traditional evaporator and condenser in our HVAC system. Instead, we merely have a hot coil and a cold coil. We don't work with a direct-expansion refrigerant that changes state. We merely move water. These chilled water systems can be used in residential and commercial applications. With almost all applications, both pipes will be insulated in the same size. You may also see an actuator on the outside, which impacts water flow and attaches on top of the valve. Chilled water systems can come in a two-pipe configuration or a four-pipe configuration. The supply water on chillers typically runs about 44 degrees (F). The water loops on chilled water air handlers may have either a two-way valve or a three-way valve. You'll generally see a two-way valve on systems with variable frequency drives (variable water flow). Conversely, three-way valves will typically be on systems with more constant water flow; the pump runs at a constant volume, so the three-way valve acts as a bypass. If you must replace a valve, make sure you use the correct valve for the application. These chilled water air handlers don't easily allow you to get readings from them. Once you factor insulation in, you may not have access to pressure ports at all. Some larger air handlers may have gauges installed, but they may not be accurate. Eric and Bryan also discuss: Insulation Diverting vs. mixing on three-way valves VAV system similarities Line voltage controls and fan speed Challenges and building maintenance staff Air bleeds Actuators Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan gets feedback on a podcast topic from Andy Holt. Per Andy's request, we discuss some intangible soft skills required to be a top-level technician in the HVAC trade. Overall, a technician needs to be aware of the people and things in their surroundings. These techs are in tune with their customer's emotions, the pets, and the space where they work. A good technician is thoughtful but has the ability to let things go and not let their bad experiences overwhelm them. Many technicians that fit both of those descriptors are calm and focused by nature, and they are often positive people; happy techs are better communicators with customers. Eye contact is important in the right amount. Customers want to know that you're paying attention to them. Customers also want to see action; they want to see you physically working on their system and taking measurements. Give the system a thorough check to find the most thorough diagnosis, even if you go into the job with an idea as to what that diagnosis is. Cleanliness is a way for you to show respect for your customer's home or site. Use drop cloths and wear shoe covers to show that you care about keeping the site clean. Cleanliness is a branch of the overall idea of professionalism. Our image of professionalism is always evolving, but in the present day, you still want to use classy language and avoid looking like a slob. Most of all, professionalism stems from a central concern for the customer; spend less time talking and more time listening. Organization in paperwork, processes, your work vehicle, and your toolbag is another one of those critical intangible soft skills. You exude professionalism when you are neat and have a structured process to guide you through your work. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Chris Stevens from HVACR Videos on YouTube comes onto the podcast and talks about some refrigeration temperature controls basics. You can check out his YouTube channel HERE. Although we have temperature controls in HVAC work, we will see slightly different ones in refrigeration work. The biggest difference is really the temperature itself; we're attempting to bring the box temperature down, so we will be dealing with much lower temperatures in refrigeration. The box and evaporator coil temperatures are the most important temperatures to be aware of in reach-in refrigeration, as they directly relate to pressures. A standard pressure control opens or closes when pressures fall or rise. Your typical low-pressure control will open on a pressure fall and close on a pressure rise. We can use these as loss-of-charge switches or use them with the pressure-temperature relationship as evaporator temperature controls. However, pressure controls can be quite inaccurate. You absolutely CANNOT "set it and forget it" with these controls; you will likely have to make some adjustments, especially if you have long line sets. We also need to consider defrost in our strategies. Constant cut-in controls are other common control strategies. These are simple controls with a sensing bulb in the evaporator coil that senses evaporator temperature as closely as possible without being a pressure control; they also turn on at a set temperature. These refrigeration temperature controls are quite accurate, but they can be difficult to use properly because they also pick up lots of other vital signs from the system. Chris and Bryan also discuss: TD vs. delta T K-type thermocouple calibration Wrap-up procedures for refrigeration jobs Self-defrosting with pressure controls Constant cut-in control sensing bulb placement Service gauges Frost buildup in medium-temperature applications Digital controls Controls based on product temperature Universal and aftermarket controls Air-sensing temperature controls Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan talks about the differences between mineral oil (MO) and POE oil, the advantages and disadvantages of using them, and when to use them. Mineral oil (MO) is what we've used for a long time. We like using it because it's very stable; it may have an affinity for moisture, but it is not nearly as hygroscopic as POE oil. Vacuum pump oil is a highly refined mineral oil, and it works so well because it's able to lock in moisture as those non-condensables get sucked out of the system. It is still not much of a solvent compared to POE oil, though. However, the refrigerant may have a hard time carrying mineral oil through the system. So, pipe size, pitch, and trapping are important considerations when you're dealing with mineral oil. POE (polyol ester) oil works much better with newer refrigerants, especially R-410a. These new refrigerants can't carry mineral oil effectively, and so they rely on POE oil, which moves with those refrigerants a lot more easily and doesn't just sit in the evaporator coil. Oil should stay in the compressor, but oil loss will happen over time and should move back to the compressor with the refrigerant. POE oil works with new refrigerants, but it also works with R-22. Overall, POE oil is very miscible, which means that it moves with refrigerant very well. However, POE oil is reactive and acts as a solvent. The POE oil can pick up contaminants a lot more easily than mineral oil, which can wreak havoc on your system. POE oil reacts with moisture to become acidic, which can lead to issues like burnout. (Note: POE oil does NOT react with mineral oil!) Bryan also covers: Refrigerant velocity Oil return Acid scavengers Retrofits Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Eric Mele returns to the podcast to discuss quality cleaning and maintenance procedures for small refrigeration systems. These small refrigeration systems include reach-in refrigerators and open-air cases on grocery sales floors. Filthy condenser coils are problems in many HVAC applications, but they're exceptionally nasty in some small refrigeration applications; proximity to food residue (grease, sugar, etc.) makes condensers get dirty quickly. Use plastic-bristle brushes to clean the bulk of the soil on the coil; you may also use shop vac extensions or even pull out coil cleaner in some cases. If you use coil cleaner, be sure to protect components from the cleaner. When doing maintenance on a small refrigeration system, try to prepare for the cleaning ahead of time. Drain cleaning and maintenance on small refrigeration systems is quite similar to other commercial systems. Drain backups are also a major cause of callbacks. It would also be wise to check that your drain pan heaters are working. You may have to use hot water in low-temp applications, as moisture may freeze on the coil. If you can't use hot water, you may consider using blower fans to avoid freezing (or just letting the unit defrost if you can). Different climate zones have unique issues. For example, in Florida, we tend to have issues with voltage from the utility companies and constant heat. So, we need to test capacitors because they fail quite often. Overall, the philosophy of good maintenance is to "do no harm." Astute observation skills are also very helpful when you do maintenance, as you'll be checking many components. Eric and Bryan also discuss: Ambient temperature ratings Radiant heat in grocery settings Using compressed nitrogen for cleaning Food prep areas "Dry" steam cleaning What if the box is not meeting temp? Cutting bleed resistors Unnecessary maintenance procedures If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan talks about the top refrigerant leak detectors, the best refrigerant leak detection practices, and some good leak detection tips. Leak detectors require some flow through them. Otherwise, they won't detect leaks. So, these tools have small pumps inside of them to move air through them for sampling. Leak detectors also require some time to warm up, so keep that in mind when you approach a job. One type of leak detector is a heated diode (sometimes called a heated pentode). It is a heated electronic leak detector that takes a sample and analyzes it within. Infrared detectors also exist, but they require you to move the tool consistently; these tools constantly recalibrate themselves, so you can't hold it still while you're using it to locate a leak. Once you confirm that you have flow, you need to determine that the detector is actually working. Make sure that your detector can pick up tiny leaks, not just large ones from cracking open a can of R-410a. So, we recommend using leak references that you can use to test your detector. One of those references is a leak test vial. Some leak detectors have a tip filter, which prevents contaminants from getting into the system. Make sure that your detector has a filter and that you change it regularly. You don't want water or other contaminants getting into your leak detector and breaking it. Another surprising contaminant is leak bubbles; these bubbles can also set off a leak detector, so be careful to manage your order of operations to avoid false positives. These tools work best if you store them in clean, dry places. It is also a good idea to keep a backup in case your main leak detector breaks or loses accuracy. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone subscribe HERE.

How does a vacuum pump work? When should you change the oil? What does that oil do anyway? Kevan Mayer of NAVAC comes on the podcast to answer these questions and more in this episode. Vacuum pumps help remove moisture and non-condensables from the system. Moisture can freeze at temperature drops in the system, and it can block refrigerant flow to the system. Moisture can also combine with POE oil to become acidic, which causes burnouts. A vacuum pump uses an impeller to bring a system under negative pressure. Many of these pumps are two-stage pumps, meaning that they have multiple chambers that push the contaminants through the pump before they get discharged into the atmosphere. As with other tools, it is a good idea to confirm your vacuum pump's operation regularly to make sure you can use it effectively. Vacuum pump oil is a type of highly refined mineral oil and should be clear. It is hygroscopic and attracts moisture, like POE oil, so you need to take care to avoid contamination. This oil both lubricates the vacuum pump and absorbs incoming moisture from the system. It's a good idea to replace your vacuum pump oil every job when you have a small pump; you may even need to change it multiple times per job. Larger pumps will typically handle a few jobs before you need to change the oil. In any case, change the oil if it starts looking amber or milky. Kevan and Bryan also discuss: Gas ballast valves Vacuum gauges and micron gauges Changing gaskets in hoses Proper oil disposal Vacuum pump size Vacuum pumps with solenoids NAVAC pumps and features Dedicated vacuum hoses Standing vacuum tests Check out NAVAC at navacglobal.com, or look for their products at trutechtools.com. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's short podcast episode, Bryan covers some tips about HVAC/R service valves and caps for new technicians. While service valves may seem simple, there are some things you should know about them before you handle them in the field. Before you connect your gauges, ask yourself if you even need to connect gauges. If you've already benchmarked the system and know what to expect, then you may be able to suffice with line temperatures. If you have a system with caps or Schrader cores and need to hook up your gauges, be careful not to cover any leaks in the cap or Schrader. You could potentially miss a leak on a cap or Schrader, so be sure to inspect those before you hook up your gauges. Service valves require gentleness and care when you take caps off and on. You don't need to overtighten caps and Schraders, as they mostly come together at an O-ring fitting or with a flare; check to make sure that you're using the correct caps and that those caps have their proper seals, if applicable. If you need to use a thread sealant, a dab of Nylog comes in handy. If you're too hard on it with a wrench, you could break the entire service valve. When you braze in or around a service valve, you'll want to protect it from heat. One of the best ways to do that is to tie a wet rag around it or use Refrigeration Technologies WetRag heat-blocking putty. (Remember, leave the Schraders out while brazing!) Overall, you'll really need to think about protecting that service valve from damage any time you work on it. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jamie Kitchen returns to the podcast and talks all about hard shut off TXVs/TEVs. He discusses bleed and non-bleed valves and why the TXV type matters to your compressor. When it comes to TXVs, there are two main types: bleed and non-bleed. The former may be referred to as a bleed TXV, and the latter may simply be called a TXV. However, OEMs may refer to TXVs as a "hard shut off TXV" (HSO), which is a non-bleed TXV. The core difference between bleed and non-bleed TXVs is the equalization speed. That equalization speed affects how your compressor runs; equalizing the system reduces the pressure differential that the compressor will have to overcome on startup. Non-bleed/hard shut off TXVs may cause the compressor to draw locked rotor amps because the pressures did not equalize. To mitigate that issue, you can put in a start cap and relay on the compressor or replace the valve with a bleed TXV. The main purpose of hard shut off TXVs is to prevent refrigerant migration and flooded starts when the system is off. The non-bleed TXV does not permit equalization, which builds pressure and but keeps refrigerant in the condenser, not the evaporator. Although the compressor will have to overcome more pressure upon startup, it will be less likely to fail due to a flooded start. However, some manufacturers may recommend using a hard start kit to overcome that pressure if you use a hard shut off TXV (even on scroll compressors!). Jamie and Bryan also discuss: Non-bleed TXVs on scroll compressors Pressure rising and falling throughout the system Opening/closing forces Superheat spring Liquid refrigerant migration Shutting off the suction line vs. using a liquid line solenoid valve Proper equipment sizing and short-cycling Charging with bleed vs. non-bleed TXVs Energy benefits Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast, we cover why both compressor and evaporator superheat matter. We also address some common confusion related to each. Evaporator and compressor superheat are two different readings that give you different indicators about the system's health. When you look at evaporator superheat, you see how far you feed boiling refrigerant into the evaporator coil. You don't want to overfeed your evaporator coil and risk flooding your compressor. However, you also don't want to starve your unit and reduce suction pressure. You'll want to stay between 5 and 14 degrees (F) of superheat at the evaporator outlet on typical A/C systems. On TXV systems, we can control superheat at the evaporator outlet. Evaporator superheat is the reading that helps you optimize your capacity. Increasing it will decrease your evaporator capacity, as the evaporator coil won't be fed as much refrigerant. The lowest possible value is your best bet for maximizing efficiency and capacity. Compressor superheat can be measured before the compressor. When you know that value, you can predict how hot your compressor will be when it runs. The temperature can increase from the evaporator outlet to the compressor inlet. Poor insulation in close proximity to the liquid line can be a cause; heat can transfer from the warm liquid line to the cool suction line. Our goal is to minimize heat gain in the suction line, so we want to insulate our suction lines and keep them as short as possible. However, you don't want the compressor superheat to be so low that you end up flooding the compressor. In most cases, you should check both values to evaluate the heat gains or losses in your suction line. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast, Jim Bergmann joins us to talk about evacuation. He discusses pulling a vacuum, conductance speed, microns, core removal, decay rate, and all that other nerdy vacuum stuff. Jim has helped develop some new BluVac hoses with AccuTools, and he's here to explain why we need those. He also explains why we need to be more educated on evacuation. While we have many good hoses today, we still have a way to go when it comes to moisture removal. Jim Bergmann has seen the need for more durable hoses that perform better when there's moisture and acids in the system. Pulling a vacuum that makes the system dry is crucial for that equipment's longevity. You cannot over-vacuum a system, so the deeper vacuum you can make, the better your evacuation will be. Evacuation often takes place on new pieces of equipment, and some people worry that deep vacuums will compromise the oil quality of those new systems. That is actually not a real issue to worry about during evacuation, and it's a piece of misinformation that makes people misunderstand the importance of evacuation. Not enough people understand how evacuation works, and that is how misinformation and distrust around evacuation spread throughout the HVAC industry. Evacuation best practices come down to the materials you use. We'd like to use a dedicated evacuation rig with the highest possible conductance speed. So, to achieve that, you'll want as few fittings/connections as possible and wide, short, high-quality hoses that are impermeable and leak-free. Remember to remove all Schrader cores and use your micron gauge away from the pump. Pull the vacuum down as deep as you can get it and do a decay test. Bryan and Jim also discuss: Degassing and dehydration Best evacuation technologies of yesterday and today Evacuation education gap TruBlu hoses Pressure, density, and air "thickness" Moisture adhesion Behavior of water Hose ratings POE oil and moisture Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's short podcast episode, Jim Bergmann and Bryan answer the age-old question: Can you really freeze water in a vacuum by pulling down too fast? Is that a problem? What should you do about it? Here is the short answer: NO. You CAN'T freeze water in a vacuum in a typical residential A/C system. First of all, you would need to have water in the system to freeze water in the system. We typically don't see large amounts of water in JVAC systems, but there could be moisture in the evaporator coil in refrigeration. Coupled with the very low temperatures, you could see freezing under vacuum in those systems. However, you will almost never see freezing moisture under vacuum in residential comfort cooling. On top of that, you would need to have enough water to freeze, not even considering the vacuum speed. We cannot achieve a vacuum that would cause that much water to freeze in a system. When you perform a decay test, the pressure rise will taper. (If it doesn't rise, then you have a leak.) When the pressure tails off, you've likely come across moisture in the system. You can usually remove that moisture without having to worry about freezing; that moisture will merely exit the system under vacuum, and it typically will not freeze. But what about water in a normal, non-HVAC vacuum? Can you freeze water in a vacuum then? YES. The water would vaporize before it freezes, and it would sublimate off very quickly on most vacuum rigs. You can check out this article and video to watch an experiment in action. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, we talk with two techs recently out of trade school. We get their perspective on their trade education and how it compares to the field. Jeremy and Blake have been kind enough to share their experiences with us and give some advice. Schooling undoubtedly gives technicians a leg-up once they got into the field. However, the knowledge you gain isn't all practical. Bookwork is still important for a solid foundation in theory, and it would likely benefit a lot of training programs. Bookwork, like trade school itself, is a good precursor to the hands-on material in the field. It also helps to do your research about classes you need to take and to see if a degree is more advantageous than a certificate or vice versa. Your education won't end upon getting that certificate or degree. In the field, you will learn something new every day (and not in the air-conditioned classroom!). A lot of your familiarity with tools will come from working in the field. However, in trade school, you will learn best practices that you may not learn from other workers in the field. When you enter the field, invest in your tools. You will work with classroom equipment, but once you enter the field, you will have to develop your own arsenal of tools—research new tools and set aside part of your paycheck to invest in your toolbox. In many ways, this is the trade with homework. You have to want to learn to be successful in this field. Every day, you will come across new problems that require more knowledge, and nowadays, you have plenty of access to online sources of information to help you tackle difficult problems. Well-rounded techs come from a solid education and apprenticeships with competent senior techs. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan talks about MicroChannel coils, what issues could happen with them, and what the best practice is to clean them. MicroChannel coils are kind of like car radiators; they have a small, honeycomb-like channel, and the sections that go between the crisscross fins carry refrigerant from the front surface to the back surface. These coils have a bit of a bad reputation. The refrigerant flows close to the surface of the coil. When the MicroChannel suffers damage, these coils can leak much more easily than other tube-and-fin coils. The channel is also more likely to be exposed to the elements and cleaners, where they can suffer from corrosion. Both alkaline and acid cleaners can cause corrosion on these coils. The manufacturers usually advise against using a cleaner. However, we know that not using cleaners can be unrealistic. When you need to clean MicroChannel coils, you should use a cleaner that is not heavily alkaline (and certainly NOT acidic!). Refrigeration Technologies' Viper cleaner is an excellent product for cleaning coils without causing damage. These small coils also hold less refrigerant than other coils. You have less flexibility with the charge, and the charge is so much more critical. A seemingly insignificant charge deviation on a normal system will have a greater impact on a system with these coils. You also have to use a chart to determine your subcooling on a spectrum to set your charge; the subcooling is not a fixed value. If you have MicroChannel coils shipped in, they may also not come with their full charge because they simply can't fit the refrigerant. Pump down is also dangerous in these coils. You can build up too much pressure and cause the coil to burst. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Eric Mele dives into the world of pumps, controls, cooling towers, and everything else related to the water side of a water source heating and cooling system. Many of these systems are water-to-water setups that use heat exchanges for heat transfer. You can listen to an introduction to water source heat pumps HERE. A cooling tower is where we reject the heat that we put into water loops. Most of these towers are of the induced-draft variety, meaning that they have fans drawing/blowing air through them. Some cooling towers are "wet" towers, where water is open to the fluid you're working with, so some of that water is lost to evaporation. Contamination can be an issue with the wet open-type towers, but strainers, chemicals, and proper planning (for location) can prevent contamination. Dry towers do not need constant refilling and need fewer precautions against contamination. These water-to-water systems use centrifugal pumps to push water through the system. These circulate water molecules, NOT compress them. Water source heat pumps get their heat from boilers, not the outdoor air in most air source heat pumps. When you have gas boilers, you have to think about your typical furnace concerns, including combustion air and carbon monoxide. Air can sometimes circulate with the water, and you'll want to minimize that as much as possible, such as via air bleeds. These air bleeds may have ball valves that you can use to purge a lot of air. Other systems may not have air bleeds, but you will still need to get air out of the system. Eric and Bryan also discuss: Makeup water float assemblies Strainers and cleaning procedures Heat exchanger configurations Water sources and quality control Water treatment Couplings and alignment Boiler configuration Bypass valves Expansion tanks Water source heat pump controls Variable frequency drives Aquastats Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan covers how to measure air velocity directly at a return or supply and what those readings tell you. Since many techs like to focus on CFM and static pressure readings, they can neglect air velocity in their measurements. Air velocity is the speed at which the air is moving. Conversely, static pressure is the force of the air against the sides of the ducts, and CFM is the air volume. We measure air mass in pounds (in the USA); when air is denser, you will have more pounds, but the volume will stay the same. We primarily measure air velocity with a vane anemometer. Air moves through the vane and spins it, which informs the anemometer. That anemometer then gives you the reading. While airflow is the ultimate measurement, it is much better to take velocity measurements than none at all. Velocity can help you determine the CFM, but that requires knowledge that some techs don't have or are simply unwilling to apply. You need to know the size of the intake and have knowledge of the open/free area of the vent. Velocity can help you determine how much throw you need to reach a certain distance. Velocity is a measure of feet per minute and can be applied to distance variables like throw. However, register sizing needs to come before measuring velocity. Velocity helps you figure out your throw and register sizing without relying on CFM measurements. Velocity can also help you identify noise issues, with higher velocities indicating noisier ductwork. To reduce air velocity in cases where you have too much, you may need to use a balancing damper to throttle it back. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast episode, Eric Mele walks us through the components of water source heat pumps, how they work, and what to look for. Water source heat pumps use water to transfer heat to and from the outdoor unit; the water takes the place of outdoor air in an air source heat pump. These units have heat exchangers and water lines, but they otherwise operate exactly the same as any other heat pump. These units have reversing valves, which are commonplace on heat pumps, and they are energized by a typical O call. Water source heat pumps almost never have defrost boards, unlike air source heat pumps. However, these units may also have auxiliary heat, such as electric heat. Capillary tubes are the typical metering devices on water source systems; the refrigerant flow can reverse through the metering device and doesn't require a second metering device, unlike air source heat pumps. Some larger water source systems may have TXV systems, and the bulb goes very close to the compressor. Water temperature will affect the cooling capacity of water source heat pumps. However, pressure and flow rates are also important factors to measure. You can measure the temperature differential across the heat exchangers and liquid line temperatures to determine if you have water flow issues. The refrigerant and water counterflow; the water and refrigerant move in opposite directions. Piping quality is an extremely important concern in a water source heat pump. If the piping fails or is supported poorly, all of that water can flood out and cause a lot of damage. Eric and Bryan also discuss: Measuring water pressure Scale buildup and neutralization Capillary tube strainers and restrictions Brazing Fasteners Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan Orr discusses the best practice methods for testing run capacitors in the field. We understand the capacitor to be a voltage storage device. We can benefit from comparing the capacitor to a balloon that inflates and deflates with electrons as the alternating current changes (60 times per second). A capacitor causes a phase shift and allows there to be current on the start winding. So, when a run capacitor fails, you won't have current on the start winding. The old-fashioned way of testing a run capacitor was to take an ohmmeter and charge/discharge the capacitor. Nowadays, we have capacitor testers, and many multimeters also have capacitance testers. Capacitance is merely a mathematical equation that you use when you compare the amount of voltage to the amount of current entering and leaving. A good way to test a capacitor on a running system is to test it under load. You take the amperage of the wire feeding the start winding and multiply it by 2652. Then, you divide that product by the incoming voltage across the capacitor to get the capacitance. While this method is probably the most practical, it still has a caveat; some meters may have a hard time getting a proper amp reading on the start winding. So, tool accuracy will also determine your success when testing capacitors under load. To increase accuracy, make sure your wires are isolated from others. Under-load testing may also be unsafe in some cases, such as with a blower capacitor. Testing with the system off is called bench testing, and it is slightly more accurate but does not represent under-load conditions. It will be more practical than under-load testing if the system is already off or if it is unsafe to test the capacitor under load. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bryan Orr talks about how the seasons affect our HVAC work and how to manage stress during the busy season. If you work in the trade, you will notice that we have busy and slow seasons. If you own a business, you understand the pressure that you're under to serve the community during those times. Hiring and training people for the busy seasons is difficult and may not be feasible for many companies. Fortunately, the busy season can bring out the good in other people who want to support their coworkers and community. The summer tends to be the craziest season, especially in the hot southern states. We work long hours and sometimes deal with angry or frustrated customers. We definitely experience times when our bodies don't feel like they can take the workload. The summer is a hard time, but that hard time also gives us a chance to build our character and take pride in our work. We remember those hard times during the cool season, winter. That's the time for Christmas parties, bonuses, and taking it easier around the shop. The seasons of our work are like the seasons of our lives. We have times where we have to work extremely hard and others when we don't need to. We got into the trade because we wanted to do something that helps others in the real world. In our work, we build up that grit and strength of character so that we can appreciate the less physically demanding days later, especially when we get into management, but we may never truly give up our work completely. HVAC technicians keep that strength of character and wisdom from the hard seasons, and they hold onto those throughout their lives. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's short podcast episode, Bryan discusses the voltage drop measurement tool, also commonly known as the voltmeter. You can also find this voltage drop tool on multimeters. You use them to check voltage drops, NOT the actual voltage. We get voltage values from a potential difference. So, we check for these differences via voltage drops. For example, you can determine if contactor pitting or carbon buildup is problematic by measuring the voltage across contact points. Your meter will read the voltage drop. We don't often deal with intentional series circuits. However, we can see unintentional series circuits when switchgear or wiring adds more resistance than it should. The voltage drops when that happens. You can also use a voltmeter to locate an open circuit; when you no longer see voltage as you walk through a circuit, you can determine that you have found an opening. An HVAC system with low current may have a cumulative voltage drop, which is the total drop of all the voltages in the system, including the crankcase heater and compressor windings. Kirchoff's second law helps explain the behavior of the voltage in a system; the law states that for a closed-loop series path, the algebraic sum of all voltages around any closed loop is equal to zero. Any time you use a voltmeter, your two leads communicate the voltage drop from one lead to the other, whether those are across contactors or different points on the same wire. When finding an undesigned voltmeter is most effective when used under load. You will see a massive voltage drop when you use a voltmeter under load; otherwise, you will see a much smaller voltage drop. Check out Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast episode, we have a conversation about the pros and cons of commercial vs. residential HVAC with Andrew Greaves. (You may know him as AK HVAC on Youtube. Check out his channel HERE and his comedy channel, HVAComedy, HERE.) In many cases, young people don't know if they want to go into commercial or residential HVAC, or residential techs may think about getting into commercial HVAC. Commercial HVAC may include RTUs, chillers, market refrigeration, or industrial refrigeration. Commercial HVAC/R also includes a lot of control systems. By comparison, residential HVAC almost exclusively deals with comfort cooling. Even though it may seem as though commercial HVAC requires more specialized schooling, that isn't necessarily the case. Schooling will especially help with commercial HVAC, but it's not required. The desire to learn is much more important than schooling. (Be willing to unlearn your bad habits, too.) If you enjoy working on large equipment and machines, commercial HVAC may be right for you. Hours are also a bit different in commercial vs. residential HVAC. In many cases, commercial HVAC still has on-call time, and the hours may be slightly more regular than residential HVAC. (However, some facilities like hospitals may require work at irregular hours.) If you wish to become an entrepreneur, you'll probably have more success with residential HVAC. The business models are very different, and you'll have more freedom with pricing when you start up a residential business. Commercial work is process-oriented per the customer, and there is a lot of negotiation that goes into a contract. (You'll also be more likely to stumble across lawsuits in commercial HVAC.) If you want to start up a business or have an entrepreneurial spirit, then residential HVAC might be right for you. We also discuss: Mechanical/technical aptitude People skills Commercial vs. residential shops Service contracts Corporate environments Commercial HVAC technologies Commercial HVAC specializations Profitability as a tech vs. a business owner Learn more about Refrigeration Technologies at refrigtech.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast, Bryan covers three things that the condenser does. He also explains where those things happen and what those they mean in terms of system operation. The evaporator coil does two things: boiling and superheating. However, a condenser does three things: desuperheating, condensing (changing state), and subcooling. Desuperheating occurs early on in the condenser, at the top. Refrigerant enters the condenser as a highly superheated vapor. Even though we have a few degrees of superheat in the suction line, the discharge line's superheat is a lot greater. (For context, the suction line will feel cold to the touch, but the discharge line will burn you.) The compressor skyrockets the superheat through the heat of compression and sends that refrigerant to the condenser via the discharge line. So, desuperheating reduces the temperature from 160+ degrees to the saturation temperature, about 100 degrees. In the middle of the condenser coil, the refrigerant stays at saturation. However, it continues rejecting heat. That is because the refrigerant is undergoing a phase change from vapor to liquid; it rejects heat in the form of latent heat even though the temperature stays the same. Once all of that latent heat has been rejected to the air, the refrigerant becomes fully liquid. Then and only then can the refrigerant start to drop its temperature. The temperature of the liquid refrigerant drops at the bottom of the condenser coil. We call that process subcooling. Subcooling refers to the temperature of a liquid below the saturation point. For example, if the saturation point is at 100 degrees but the liquid refrigerant is 95 degrees, you will have 5 degrees of subcooling. In general, a common subcooling range is 8-14 degrees. Learn more about Refrigeration Technologies at refrigtech.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Many techs have said, "That's the first thing you should have learned in school." In today's short podcast, Bryan talks about the four rules that have his vote for the first things to learn in school. These four rules don't just apply to HVAC work; they apply to science and the world as a whole. They describe how the forces in our world work in our HVAC careers and our everyday lives. The overarching theme of these rules is that high goes to low. Gravity is the prime example of this rule; if you drop something from a high place, it will fall to a lower place. There is a potential energy difference between high and low, whether you apply that to a ball rolling down a hill, voltage, or a sine wave. The first rule is that high pressure goes to low pressure. The compressor applies lots of pressure to the low-pressure refrigerant inside of it. The second rule is that high temperature goes to low temperature. We transfer heat from the inside of the house to refrigerant inside the evaporator coil. (Remember: temperature is an AVERAGE measure of molecular activity.) The third rule is that high voltage goes to low voltage. Electrons move from the higher energy state to the lower energy state. The fourth rule is that high humidity goes to low humidity. For example, two air masses with different humidity contents can be separated by a cloth. The higher-humidity air mass will diffuse some of its moisture across the cloth to the lower-humidity air mass. This process creates a stasis across the two air masses. Everything in the world tends towards equilibrium. Learn about Refrigeration Technologies at refrigtech.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.