HVAC School - For Techs, By Techs

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.

In this episode, we speak with the founder of Refrigeration Technologies, John Pastorello. He also tells us all about chemicals, cleaners, and HVAC coil cleaning. John Pastorello started out working as a chemist before becoming an A/C installer. He initially planned to return to a lab job, but he found his niche in HVAC work. He took his chemistry experience to his HVAC work to develop better chemical products. It all started with his decision to make a better leak detector fluid (Big Blu). However, John knew that you can't build a company around one product, so Refrigeration Technologies was born. An ideal condenser coil cleaning starts with having the correct dilution ratio. There is a bell curve of effectiveness, and using too much cleaner can be as ineffective as using too little cleaner. Typically, we can optimize soil removal with a dilution of one part cleaner to five parts water. You can pre-rinse with enough pressure to "punch through" the coil. Then, you can apply the foam detergent. Foam guns can make it easy for soil molecules to bond to the detergent. John recommends starting at the bottom and working upwards, keeping the foam gun close to the condenser the entire time. Give the detergent some time to penetrate through the soil, and then rinse. Repeat the process for maximum effectiveness, upping the dilution ratio this time. Evaporator coils can develop a unique problem: biofilm. Very few cleaners attack that protein biofilm. EVAP+ coil cleaner contains enzymes that can digest biofilm and remove it over time. John and Bryan also discuss: Acid vs. alkaline products "Green" products and performance Cleaning products and bodily hazards (itching, scarring, etc.) Foam cleaning Coil brushing Testing new chemicals Chlorine corrosion on aluminum oils Pan and drain cleaners Visit the Refrigeration Technologies website and learn more about their products at refrigtech.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast episode, Jonathan Romberg comes on to discuss how the Danfoss ERC 213 works and reviews its parameters with us. Timestamps: 10:30 – Key Features 10:41 – Voltage Protection 10:56 – Compressor Protection 14:43 – Applications 15:15 – App 0 No predefined application 15:28 – App 1 Medium temperature ventilated refrigeration units with timed natural defrost 15:52 – App 2 Medium temperature ventilated refrigeration units with timed electrical defrost 16:03 – App 3 Low temperature ventilated refrigeration units with timed electrical defrost 16:13 – App 4 Medium temperature ventilated refrigeration units with electrical defrost (by temperature) 16:26 – App 5 Low temperature ventilated refrigeration units with electrical defrost (by temperature) 16:37 – App 6 No predefined application with a simplified list of parameters 19:45 – Sensors 22:06 – Basic Groups of Parameters 23:09 – r-- Thermostat 23:12 – r00 Temperature setpoint 23:24 – r01 Differential 23:32 – r02 Min setpoint limitation and r03 Max setpoint limitation 24:02 – r04 Display offset 25:19 – r05 Display Unit (°C/°F) 25:33 – r09 Calibration of Sair 25:47 – r12 Main switch 27:17 – r13 Night set back 27:48 – r40 Thermostat reference displacement (offset temperature) 28:30 – r96 Pull-down duration and r97 Pull-down limit temperature 29:06 – A-- Alarms 29:13 – A03 Delay for temperature alarm during normal conditions 30:15 – A12 Delay for temperature alarm during pull-down/start-up/defrost 31:00 – A13 High-temperature alarm limit (Cabinet/Room) 31:34 – A14 Low-temperature alarm limit 31:55 – A27 DI1 delay and A28 DI2 delay 32:17 – A37 Condenser high alarm limit 32:41 – A54 Condenser high block limit 33:45 – A72 Voltage protection enable 34:03 – A73 Minimum cut-in voltage and A74 Minimum cut-out voltage 35:04 – A75 Maximum Voltage 37:37 – d-- Defrost 37:49 – d01 Defrost method 38:32 – d02 Defrost stop temperature 38:50 – d10 Defrost stop sensor 40:51 – d03 Defrost interval 41:16 – d04 Max defrost time 43:38 – d05 Defrost delay at power up (or DI signal) 44:29 – d06 Drip delay 44:49 – d07 Fan delay after defrost 45:49 – d08 Fan start temperature after defrost 47:21 – d09 Fan during defrost 47:40 – d10 Defrost stop sensor (part II) 48:16 – d18 Compressor accumulated runtime to start defrost 50:04 – d19 Defrost on demand 53:26 – d30 Defrost delay after pull-down 53:53 – F-- Fan control 54:03 – F01 Fan at compressor cutout 55:00 – F04 Fan stop evaporator temperature 55:51 – F07 Fan ON cycle and F08 Fan OFF cycle 56:28 – c-- Compressor 56:37 – c01 Compressor minimum ON time 56:47 – c02 Compressor minimum OFF time 57:01 – c04 Compressor OFF delay at door open 57:51 – c70 Zero crossing selection 58:22 – o-- Others 58:37 – o01 Delay of outputs at startup 59:11 – o02 DI1 configuration 1:01:36 – o05 Password 1:02:08 – o06 Sensor type selection 1:02:27 – 015 Display resolution 1:03:31 – o23 Relay 1 counter, o24 Relay 2 counter, and 025 o24 Relay 3 counter 1:04:13 – o37 DI2 configuration 1:04:52 – o61 DI2 configuration 1:05:07 – o67 Save settings as factory 1:05:39 – o71 DO2 config 1:06:23 – o91 Display at defrost 1:07:04 – P-- Polarity 1:07:06 – P73 DI1 input polarity and P74 DI2 input polarity 1:07:32 – P75 Invert alarm relay 1:07:59 – P76 Keyboard lock enable 1:08:21 – u-- Readouts 1:08:30 – u00 Controller Status 1:09:37 – u01 Air temperature (Sair) 1:10:12 – u58 Compressor relay status, u59 Fan relay status, u60 Defrost relay status, and u63 Light relay status Find out more about the Danfoss ERC 213 HERE. 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 podcast, we discuss the real significance of superheat and why it is much more than "a way to set the refrigerant charge on a fixed metering device." Superheat is the temperature of a vapor above saturation. Many people use it to set the charge on a piston or fixed orifice, but that's not its only purpose. Superheat is a much more important reading than that, and you can take that measurement at a few different places. For example, most of us measure it outside. However, to determine how the system is feeding the evaporator coil, we would take superheat at the evaporator outlet (6-14 degrees is normal for a TXV). However, superheat matters regardless of the metering device type. Zero superheat indicates that the refrigerant is still at saturation; it is in a mixed state, not entirely vapor. So, we know that we are "overfeeding" the evaporator coil. The boiling process does not finish in the evaporator; it continues into the suction line. Overfeeding is a problem because our evaporator might not boil off all the refrigerant, and we could send liquid to the compressor. The system may be overcharged, or the evaporator load may be too low. Excessive superheat indicates that the refrigerant is boiling off too quickly in the evaporator coil. In those cases, we are starving or underfeeding the evaporator coil. The boiling process ends too early in the evaporator coil. The system may be undercharged or have too much load on the evaporator coil. When our superheat is within the proper range, we are feeding the evaporator coil correctly. The majority of that evaporator coil is being fed with boiling refrigerant. 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.

This is the story of WITH JOSHUA NICHOLLS FROM PLATINUM ELECTRICIANS and how he went from pulling wire, to creating a franchise empire to giving back.

In today's podcast, Jon Bennert with Air Oasis talks about photo-catalytic oxidation (PCO) air purification. He explains how it works and what it does. The NANO products are PCO-type technologies. These technologies were initially developed for NASA storage systems on the International Space Station. Photo-catalytic oxidation (PCO) products work to reduce or sterilize pollutants or organisms in the air by using light. Sunlight produces UV rays that can kill nasty germs in the air; PCO products work similarly and may have UV lamps or not. (NANO units use UV lighting.) The UV isn't all that effective by itself. However, UV light can produce pollutant-fighting ions when the UV hits the coating within the air purifier. These ions are typically hydroxyl ions, which are more effective than ozone but don't last very long. So, PCO products are most effective when they have a large surface area with the catalyst. You can get all sorts of bacteria, yeast, and fungi inside a home. Humidity will usually only make those worse. Not to mention, you also have VOCs from cleaners and building materials, which may smell nice but greatly reduce your air quality. Humans also create plenty of pollution through humidity and dead skin cells. Air purifiers can help you deal with all of these air quality reducers. The NANO is unique, as it can run only when the fan is on and reduce ozone byproducts in your ductwork. Bryan and Jon also cover: UV lighting in the ductwork Simple organisms vs. complex organisms and defense mechanisms Ozone and ozone-generating equipment PCO byproducts and efforts to reduce those NANO sizing How Air Oasis tests the product's cycles NANO vs. competitors Improvements to the NANO over time How techs can recommend and sell IAQ products more effectively Air quality testing Find out more about Air Oasis at airoasis.com. 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 this episode, we talk about air as a form of matter. We cover air volume, density, weight, and mass and why it matters to you. So, air has weight and takes up space. When we measure air, we typically measure it by volume (CFM or cubic feet per minute). When we say that air takes up space, we are referring to air volume. A cubic foot of air is equivalent to a 1'x1'x1' box of air. When we measure CFM, we measure how many boxes of air we move per minute. We usually want around 400 CFM per ton, though the exact number varies by system, function, and ambient conditions. Lower CFM per ton is better for moisture (latent heat) removal, while higher CFM per ton is better for sensible heat removal. Air also has weight. When we are at higher altitudes, the air is thinner and less dense. Therefore, the air has less weight. Standard air weighs about 0.75 pounds per cubic foot (box of air). If you multiply the 400 CFM per ton standard by the standard air weight, you get 30 pounds of air per minute. That pounds-per-minute value is what we call the mass flow rate. The air density affects mass flow rate; temperature and relative humidity can change the density of air. So, the volume is the box, but density (which affects mass) is what's in the box. Even though our goal is to move pounds of refrigerant (mass), we care about CFM (volume) because fans move air regardless of density. The blower affects the CFM, but the mass flow rate is more important to the coil. We have to adjust our volume flow rate to achieve a proper mass flow rate. 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, Ralph Wolf comes on and discusses inverter equipment. He also talks about Mitsubishi, Bosch, and what he's been up to nowadays. An inverter system can vary its output of rated capacity. Inverter equipment makes load matching much easier and is generally comfortable. These systems maintain temperatures in tighter ranges and remove more moisture with longer runtimes. Mitsubishi is one of our top ductless systems at Kalos. Due to building codes, they are one of the only systems we can use in sunrooms and lanais. However, the building codes technically allow those systems to be used for dehumidification. Mitsubishi mini-splits can perform below average if they aren't sized correctly (even if they appear to be correctly sized). Bosch is another manufacturer that makes inverter-driven equipment. Like Mitsubishi, Bosch is based in Asia but has been making massive strides in the American market. They use the same Y and O calls you'd see on typical heat pumps. Bosch equipment can ramp its compressor up and down to accommodate the load. You can also use a larger unit on a smaller air handler. You can also choose from a variety of coil temperatures and adjust the fan to reach your desired dehumidification. However, inverter board issues are quite common right now. We should expect some of these issues to clear up with future versions of the equipment. Breakdowns are normal for new technologies, but Bosch has gone above and beyond to fix issues by bringing their engineers to the USA to analyze our faulty equipment. The future is bright for Bosch and inverter technology. Bryan and Ralph also discuss: Choosing new inverter equipment Improper compressor operation Compressor sizing effects on operation ECOER systems Inverter technology and controls Short cycling prevention Heat dissipation issues in capacitors Ductwork for inverter equipment 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.

Part 2 - Bert (Kalos Tech) and Keiran (Kalos Apprentice) join Bryan in the studio to talk through the basic refrigerant circuit and how it functions. They talk compressor, condenser, metering device, and evaporator as well as the four lines and the states of the refrigerant as it travels. The four lines that move refrigerant are the suction line, discharge line, liquid line, and expansion line. The suction line moves cool superheated vapor from the evaporator to the compressor. Then, the discharge line moves very hot superheated vapor from the compressor to the condenser. The liquid line runs warm subcooled liquid from the condenser to the metering device. Of the four lines, the expansion line is a bit controversial, as it doesn't even exist in some systems. It runs from the metering device to the evaporator and expands the liquid refrigerant so that some of it can flash at the evaporator inlet. You may see an expansion line on mini-splits, but many typical residential split systems will lack an expansion line. The suction line draws vapor to the high side of the system, and the discharge line discharges high-pressure vapor to the condenser. A liquid line gets its name from the fact that it carries liquid to the metering device. The expansion line gets its name because it expands the liquid/vapor mixture (reducing pressure, continuing the metering device's job). We also discuss: Evaporation vs. boiling Condensing temperature over ambient (CTOA) Superheat and subcooling Line dryers Saturation Feeding evaporator coils Where to measure superheat

Part 1 -Bert (Kalos tech) and Keiran (Kalos apprentice) join Bryan in the studio to talk through the basic refrigerant circuit and how it functions. They talk compressor, condenser, metering device, and evaporator as well as the four lines and the states of the refrigerant as it travels They talk about the compressor, condenser, metering device, and evaporator as well as the four lines and the states of the refrigerant as it travels. We have already covered all of the basic components in earlier podcasts, which you can check out HERE; we focus more on accessories, refrigerant movement through the circuit, and scientific concepts in this episode. We also discuss: Pumps vs. compressors Refrigerant and air-cooled compressors Flooding a compressor with liquid refrigerant Crankcase heaters Temperature vs. heat vs. BTUs VRF vs. ductless

In today's podcast, I talk with Corbett Lunsford about his new show about home performance and diagnosis. Home Diagnosis airs on PBS in winter 2018. Even though Home Diagnosis mostly deals with building performance, HVAC work is a large component of overall home performance. Corbett Lunsford used to be a pianist before becoming a building performance expert. He was already familiar with media and decided to launch a YouTube channel. The goal of the YouTube channel was to bring visual information and practices to the masses. Since then, he has been working to create a much larger mass media project to let HVAC professionals and consumers know about building performance. Home Diagnosis is Corbett's means of bringing awareness to whole-home performance as buildings become much tighter. The main goal of Corbett's TV show is to put home performance on the same level of awareness as car performance and athletic performance. Many factors contribute to comfort, but it is not all the responsibility of the HVAC technician. The home performance field addresses ductwork and the overall design of the house to provide the most accurate and holistic comfort solutions. The TV show also empowers consumers to talk to experts to help them achieve their comfort targets, not just request a certain repair. While HVAC technicians make up for losses in a building enclosure, building science assesses the issues with the enclosure. Bryan and Corbett also discuss: Contractor mistakes Good and bad practices for fixing ducts "Seeding" your clients and building trust Giving customers options to choose other contractors Sponsorship offers and participation Humid Climate Conference Learn more about Home Diagnosis HERE. Check out Corbett's Home Performance YouTube channel HERE. Check out Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Sean Harris with Positive Energy and Aeroseal Austin sat down with me at the humid climate conference and talked about how to seal ducts from the inside with Aeroseal. We regularly see air leakage by poor connections, especially when we deal with flex ducts. When a house comes under negative pressure, it draws a bunch of air in from the outdoors or unconditioned spaces. Unfortunately, that air can be very low-quality in humid climates. The humid air can be even worse if it comes from an unconditioned space where you have leaky supply ducts. So, we can prevent that nasty attic air from coming in if we seal ducts from the inside out. Aeroseal goes inside the ducts and is a good sealant that can be compared to Fix-A-Flat for a car tire. When pressurized air leaks from the duct, Aeroseal makes its way to the leak and expands over it. Aeroseal doesn't coat the ductwork; it merely travels to leaks and seals them up. Aeroseal looks like a mist and can seep out of leaks. So, as an extra measure of caution, be prepared to protect a customer's belongings in an attic or crawlspace. However, sealing ducts requires a holistic approach. We need to perform quite a few tests to get an idea of the building envelope and duct design before we consider ways to seal or replace the ductwork. Sean enjoys paying attention to duct sizing and understands that sealing ducts could make a customer's comfort issues even worse in an oversized duct system. So, Aeroseal is a great product for leaky ducts of a good size. Aeroseal is a long-lasting solution for duct leaks, but it is not a magical fix-all product. Learn more about Aeroseal HERE. Check out Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Today's short episode covers five things residential techs need to consider when tasked with doing maintenance on a commercial system. We mostly talk about light commercial package unit maintenance in this episode. If you come across fresh air filters, be sure to wash those. Some commercial units have economizers that bring in fresh air, but not all fresh air is high-quality. Wash those filters to avoid pollen and other types of outdoor gunk buildup. Then, you'll want to check and adjust belt tension. Make sure you adjust the belt in each direction correctly; don't get them too tight. Otherwise, you might break or stretch the belt. You may also wear out the bearings or cause higher amperage on the blower motor. In general, you want the belt to be tight enough not to slip off and no tighter. We recommend using the Browning belt tension tool. You may also consider replacing the belt if need be. You'll also want to align pulleys. Don't just align the edges; align the entire pulley. If you're dealing with sheaves, you can adjust those to tweak your CFM rate. Make sure the motor mounts are square, too. The next maintenance step is familiar with residential techs: properly wash the condenser coils. However, you may have to "split" the coils; you'll pull them apart and put them on a piece of wood as you separate them. Even though it sounds difficult and time-consuming, splitting the coils is the only way to do a thorough cleaning. Lastly, you'll want to check the phase balance on three-phase equipment. Phase imbalance can lead to the death of a motor; more than 2% of imbalance can cause issues, and 4% indicates a severe problem. 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, Lee Andrews with Andrews Filters talks about the complicated and important topic of air filters and filtration. He also explains why they should matter to you and your customers. As indoor air quality (IAQ) becomes more important in HVAC work, air filters will become even more important than they already are. We classify air filters by MERV ratings. MERV ratings describe the ability of filters to capture finer particles; a MERV 11 filter will catch a lot more particles than a MERV 6 filter. Most air particulates are an average of 0.4 microns large, but most air filters only catch 5-15% of those particulates. The filter industry aims to catch smaller and smaller particulates to improve indoor air quality, protect equipment, and keep consumers healthier. However, MERV is not a comprehensive value for efficiency. The actual filter media is also important for a filter's efficiency. Higher-quality, finer fibers will have a higher probability of catching smaller particulates. Having a greater surface area (more pleats) also increases performance. The media has a small charge, which helps a filter collect particles. Humidity, particulate insulation (dirtiness), and alcoholic pollutants (such as diesel) can discharge a filter and reduce efficiency. Many people use MERV 8 filters, but very few understand the difference between MERV 8 and MERV 8A filters. The addendum of the MERV test (A) uses an alcohol-type product to remove the charge. So, MERV-tested filters without the addendum test can actually perform at a lower-rated level. For example, a MERV 8 filter could perform more like a MERV 5-6 filter. Bryan and Lee also discuss: Electrostatic charge and airflow MERV 8 vs. MERV 8A Loading and unloading Board materials Filter design and sizing Talking to customers about filters Energy savings Check out Andrews Filter's website at andrewsfilter.com. Check out Refrigeration Technologies' chemical products HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Have you ever struggled to repair a leak in an all-aluminum coil? Lance Robinson with SolderWeld talks about his product to do just that and makes a convincing case for aluminum repair. We've been using aluminum for several decades before the shift to copper; unlike copper, aluminum is corrosion-resistant. However, copper is typically better for brazing due to its heat transfer properties and ductility. If we can get to a point where we can use aluminum for the same uses as copper, we will probably see a shift to aluminum due to its durability. SolderWeld has recently made an aluminum repair product. Alloy-Sol is a solder, meaning that it works below 840 degrees Fahrenheit, and it gives techs plenty of time to work without worrying about melting the aluminum. Alloy-Sol works with a powdered flux, which goes on in a white paste that bonds to the aluminum and cleans it. When the flux turns clear, you can begin applying the solder to join the surfaces. You can melt the rod into your repair so long as you have that bond. You can use Alloy-Sol to perform COMPLETE aluminum repairs, not just temporary repairs. When applying heat, make sure you apply heat perpendicularly to the repair. Repairing aluminum requires perhaps a bit more focus and finesse than copper brazing, but it is still a relatively easy process. We may not have considered aluminum repairs in the past, but they are worthwhile with the correct solder products. Bryan and Lance also discuss: Aluminum's low melting point Torch usage and heat application Working with microchannel coils Training techs to repair aluminum Cleaning aluminum Fittings for aluminum piping Aluminum repair limitations Alloy-Sol in the auto body industry SolderWeld's history Learn more about SolderWeld HERE and Alloy-Sol HERE. Check out 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 covers the most misunderstood portion of Ohm's law explained masterfully from 1921: when resistance goes up, amps go down. The American Electrician's Handbook (1921) contains a lot of electrical knowledge that holds up in the present day. (The electrical testing methods don't hold up quite as well, though...) One of those principles that hold up is the idea that amps go down as resistance goes up. Amps refer to current (electrons). The ohm is the unit of electrical resistance, and it is NOT the same as mechanical resistance, such as in a compressor with locked-up bearings. The common "water" analogy for electricity works quite well for helping us see how voltage enters the equation. Electromotive force (EMF) is comparable to water pressure, which pushes water in a hydraulic piping system. So, you can compare voltage to PSI. The current (amps, I) is comparable to the flow of water. So, if you have more pressure inside a hydraulic system, more water will flow out; as voltage (V) increases, amperage also increases. That analogy also explains why you can have volts without amps; there can be plenty of water pressure behind a closed valve, but there will be no flow. Additionally, a smaller pipe has more resistance than a large one. So, less water (amps, I) will flow through a pipe with greater resistance (ohms, R). When resistance goes up, amps go down; the water analogy illustrates that principle very clearly in terms that we are familiar with. With all these in mind, you can yield the three following equations that make up Ohm's law: I = V/R V = I x R R = V/I Learn more about Refrigeration Technologies chemical products 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, Jamie Kitchen talks about refrigeration controls and applications. He also tells us about the Danfoss ERC 213 universal digital controller. Electronic refrigeration controls tend to have greater accuracy and flexibility than traditional electromechanical controls. These electronic controls also allow you to perform many more tasks than traditional ones. Electromechanical controls also wear out and lose their accuracy over time. When you deal with applications that require various temperature, humidity, and defrost requirements, you can use electronic controls to choose between several options for the defrost method, defrost stop temperature, fan delay after defrost, etc. You can also put voltage and head pressure protection measures in place. You can optimize defrost and box temperature with electronic controls, but you can't control evaporator coil feeding. However, EEVs work well with these refrigeration controls and can adjust evaporator coil feeding. The ERC 213 has temperature and defrost sensors, but you can also configure it to work with other sensors, if you prefer. The ERC 213 has seven different application settings (0-6). In cases where a preset option will suffice, choose between Apps 1-5. (Consult Resources for the ERC 213 installation guide, which explains each application.) However, you shouldn't assume that the electronic controls will have the same settings as mechanical controls. If you want to learn the full functionality of the ERC 213, you can use Apps 0 & 6 to customize parameters. Just remember to supply the correct voltage to the controller (120v). Bryan and Jamie also discuss: Customizable settings Superheat controllers and EEVs How defrost requirements change seasonally Controlling compressors Ice machines and restaurant refrigeration equipment Resources Find out more at Danfoss.com, and check out the ERC 213 installation guide to learn more about the ERC 213. Check our 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, Adolfo Wurts from Arbiter comes on and debates why a tech would want to use a manifold over wireless probes and vice versa. In our industry, we are likely to see a trend of moving towards wireless equipment that connects to a single device. Wireless connections and digital displays may save us money on tools and allow us to store and interpret data more efficiently. However, a manifold can help you recover refrigerant, whereas probes cannot. Manifolds also have sight glasses, which help you check for overfeeding; probes do not offer you much help on that front. Manifolds can also fit into tight spaces a bit more easily than probes, but probes have already come a long way and will continue to get better. Manifolds may feel heavier and seem more durable, but wireless probes are actually light yet hardy, and you don't have to worry about cracking screens. Probes and manifolds are probably similarly hardy, but probes are lighter and have fewer components to damage. Probes also have a massive edge over manifolds in the area of contamination prevention. Using your phone with probes has its advantages and disadvantages. Unfortunately, you expose your phone to situations that may damage it. However, you can access all of your readings in real-time from the phone. Your phone also has more processing power, and some apps can perform advanced calculations. You can avoid exposing your personal phone to field damage by using an older, cheaper phone just for field usage. So, as our society and industry become more tech-savvy, probes will continue to improve. Probes that have an edge now will still improve, and you may want to consider using probes over manifolds. However, you may want to have additional hoses and a sight glass. Adolfo and Bryan also discuss: UEI Hub kits Tool misuse and damage through improper storage Software in HVAC/R apps K-type thermocouples Using probes in ductwork Dehumidification Find out more about the UEI hub kits HERE. 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, Phil Barr joins Bryan to explain sizing for wires and breakers in HVAC/R work. You will be able to select breakers, conductors, and fuses properly and without confusion. Phil Barr is the leader of the electrical division at our business. HVAC/R equipment may have hermetically sealed motors. Unlike squirrel-cage motors, hermetically sealed motors have an outer shell that makes it impossible to access the inner components. Semi-hermetic equipment, such as some compressors, look like hermetic equipment but can open up. Wire sizing varies between hermetically and non-hermetically sealed motors, and the NEC explains the wire sizing requirements, but YOU need to know the context for those requirements. Once you know your equipment type, check the nameplate with a rating, such as MCA, RLC, branch circuit selection, etc. The manufacturer will establish that rating, and you will use it to look up the correct wire sizing requirements. Wire insulation and conductor type also dictate the sizing and installation requirements. Conductor length and voltage drop also affect wire sizing. Fuses or circuit breakers prevent shorts. Shorts are undesigned paths with little to no resistance, so fuses and circuit breakers protect equipment and buildings from overcurrent due to shorts, NOT thermal overload. So, you use MOCP as a guideline for sizing your breakers. Thermal overload protection keeps conductors from melting under overload conditions. If you want a breaker that is under the MOCP value but it exceeds the MCA and the terminations are rated correctly, you can typically use a breaker between the MCA and MOCP. However, you will still want to follow manufacturer recommendations and check with your AHJ. Phil and Bryan also discuss: MCA (minimum circuit ampacity) "Undersized" conductors in new constructions Reducing voltage drop MOCP and related terms Inrush current Adjustment factors If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast episode, Johnathan Jones from Clean Comfort, Ultra-Aire, and Therma-Stor talks to us about humidity, dehumidification, and ventilation. Relative humidity (RH) is a moisture content ratio that depends on temperature. Hotter air can hold more moisture, and colder air can contain less moisture. You can increase or decrease the temperature to change the relative humidity, but the dew point stays the same. The safest humidity range is between 40-60%. It is typically harder to add humidity to an arid place than to remove humidity from a tropical place. We work to control the dew point (keeping it below 55 degrees). When we keep our indoor temperatures well above the dew point, we don't have to deal with condensation and moisture, which leads to microbial growth. We encounter two conflicting schools of thought: reduce the fan speed to control humidity or raise the fan speed to keep the ducts warm enough to prevent "growth." However, a dedicated dehumidifier takes care of the space without requiring fan speed changes. A lot of indoor moisture comes from our bodies, such as by breathing and talking. Local ventilation, especially during cooking and showering, helps reduce moisture ONLY if it sucks in quality outdoor air. Ventilation strategies can be balanced or imbalanced. Balanced ventilation helps us avoid negative ventilation; mechanical ventilation brings the building under positive pressure. When a building is under positive pressure, air gets pushed out to maintain balance. Additionally, pollutants tend to stay out. However, positive pressure can cause condensation to occur in colder climates and works best alongside a dehumidifier. We also discuss: Moisture units (pints, pounds, grains) Infiltration Encapsulated attics ERVs in coastal states Ventilating dehumidifier setup Comfort differences based on humidity alone Latent and sensible capacity Hot gas reheat applications Dehumidifiers and energy efficiency Check out Clean Comfort HERE, and check out Therma-Stor HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE. Check out Refrigeration Technologies HERE.

In this short episode, we replace a dirty "M" word (mold) with another "M" word (moisture) that gets to the root of the problem. "Mold" and "mildew" can freak out your customers. For years, I've refrained from saying "mold" at my own company and trained my techs to avoid it AND "mildew." Instead, we have called it "biological growth" or "organic growth." Those still aren't great. Just recently, my friend Joe Medosh suggested referring to fungal growth as a "moisture problem" instead. "Moisture problem" is a fact-based and less disgusting term. We can focus on solutions with indoor air quality (IAQ) to address the overarching issue that causes the growth, not just the nasty growth. In some cases, parts of the home may hit the dew point in colder temperatures. So, drywall is particularly vulnerable to falling to dew point if the building envelope has been poorly sealed. So, we have a practical means of reducing relative humidity below 55%. We can also seal the envelope better and address potential issues related to infiltration. A duct with poor or compressed insulation may also be prone to "moisture problems." We can address those "moisture problems" by properly strapping the duct. In cases when air handlers sweat by an improperly sealed duct, we seal the duct correctly to nip the problem in the bud. In the case of sweating vents, we must analyze the supply air, check the blower fan speed, and look for restrictions. Make sure all components are clean and that you seal up any leaky areas. Remember, "moisture problems" do NOT occur because hot meets cold! The moisture content and dew point are the key factors, not just a temperature differential. If you have an iPhone subscribe to the podcast HERE and if you have an Android phone subscribe HERE.

Here is part 2 of the discussion with Trevor Matthews about the causes and prevention of air conditioning and refrigeration compressor failure. Slugging occurs when the compressor attempts to compress oil or liquid refrigerant. A telltale sign of slugging is valve plate damage. On a semi-hermetic compressor, you can remove the screws on the head to access the valve plate. Wrist pin wear occurs during slugging the wrist pin is between the rod and the piston; you should test the wrist pin to see if it makes a knocking sound before you dismiss all other possibilities and replace the valve plate. Overheating occurs when there is a system-related issue. Compression ratio is an indicator of overheating, but few technicians check it often enough. A requirement for external cooling and dirty condenser coils can cause overheating. Overheating also causes oil issues; when a compressor gets too hot, oil breaks down and loses its ability to lubricate the bearings. Oil loss is a tricky cause for failure; it is hard to notice without a sight glass. Short-cycling can lead to oil loss over time, and bearings will begin to wear when there isn't enough oil to lubricate them. Contamination usually occurs when moisture corrodes the copper plating and introduces acid to the system. Acid and sludge are the most common contaminants. Proper reaming practices also keep copper out of the system and reduce the risk of acid contamination. Trevor also discusses: Slugging in scroll compressors Sight glasses and oil measurement System load and suction pressure Maintaining design compression ratio "Blow by" Oil separators Replacing line dryers Components to troubleshoot and inspect Verifying System Operation Sheet from Emerson http://hvacrschool.com/Emerson Verify Diagnosing Compressor Failures from Emerson http://hvacrschool.com/CompFailures