HVAC School - For Techs, By Techs

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

In this short podcast, we start the conversation about "Energy? Compared to What?" and explore several energy comparison examples. When we think about energy, we can confuse some terms. For example, temperature and heat are related but NOT synonymous. Temperature is an average measurement of heat energy; when many molecules move at a bunch of different speeds, the temperature represents the average speed of those molecules. Temperature does NOT measure total heat content. Voltage and amperage are two more confusing terms, and they get even harder to understand and differentiate when you throw "power" around. In most diagnostic cases, we usually measure things to compare them, such as using a voltmeter to measure a difference in electrical charges. We could compare the usage of a voltmeter to a temperature difference between two rooms. The wall between the rooms presents resistance between the temperatures of the two rooms (R-value, which affects energy transfer), and the voltage is analogous to the potential difference between the rooms. In the HVAC industry, we can witness energy differentials in temperature, charges, and pressure. Resistance gets in the way of these differentials reaching equilibrium and must be accounted for in our readings. Resistance affects the rate of energy transfer; that resistance can show up as friction, R-value, and other values that affect the total amount of energy transferred. Many techs also go wrong when they assume that a 120V blower motor draws twice as many amps as a 240V blower motor. In truth, the 240V blower requires twice as many amps to hit the same work target. In a 240V motor at 120V, it would draw far less amperage and result in less than half the usual horsepower. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast, we talk with Trevor Matthews with Emerson. He tells us about the causes and prevention of air conditioning and refrigeration compressor failure. Most compressors don't die a natural death... they're murdered. Of course, that's to say that installation and maintenance play a major role in the compressor's operation and lifespan. Electrical and mechanical failures are the two broad causes of compressor failure. When it comes to electrical failures, Trevor often sees single-phase compressors fail early when their electrical components don't receive proper inspections and care. For example, contactors may go too long without inspection or replacement. Three-phase compressors are also prone to phasing issues and may run backward. Common mechanical failures deal with oil in the system. Oil lubricates the bearings inside the compressor. Unfortunately, that oil can mix with liquid refrigerant, become diluted, or experience acid contamination. Some oil-related failures include floodback, flooded starts, slugging, overheating, oil loss, and contamination. Compressors cannot compress liquids, so many of them fail when the refrigerant condenses to a liquid inside the compressor. Many failures occur because technicians don't think they have enough time to troubleshoot or inspect the whole system. Trevor recommends setting up a checklist with all of the tests you need to perform. Trevor also discusses: Service replacement compressors vs. OEM compressors Megohmmeter usage Causes of floodback/flooded starts Compressor superheat Suction accumulators Bearing wear Temperature control and pump cycles for controlling flooded starts Verifying System Operation Sheet from Emerson http://hvacrschool.com/CompFailures

In today's podcast episode, we talk with system and duct design educator Jack Rise about ACCA Manual J load calculation and Manual S system selection. Many people know about Manual J, but relatively few techs follow it properly. When people attempt to do Manual J calculations, many of them go wrong when they overestimate the difficulty of the equations in Manual J. However, many of these techs do better when they can use software like Wrightsoft to help with their load calculations. The best way to approach load calculations is to develop confidence in software programs and field experience (sizing equipment and sealing ductwork); you are more likely to make mistakes if you put all of your confidence in one or the other. Some techs also don't take the time to measure buildings properly if they are either over-reliant on technology or too confident in their field skills. Manual S is all about equipment selection after the load calculation. However, much of the manual is not useful for fieldwork. The rules are also not as regionally thoughtful as they could be, especially regarding furnace sizing and the consequential heat loss. Manual S is only useful if you perform a Manual J calculation first and use that result as a guide. Rise does not believe that Manual S is bad, but he thinks it gives installers way too much leeway on sizing as it stands. Jack and Bryan also discuss: Wrightsoft Manual J practices in different types of buildings Envelope leakage in retrofit applications Most important chapters of Manual S Accounting for sensible and latent heat load New ventilation requirements Odors, cooking, and building design Increasing airtightness in building construction Encapsulated attics Learn more about ACCA standards and codes at acca.org. Learn more about Wrightsoft HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast, Bill Johnson shares his practical tips to make low-voltage electrical diagnosis easier in HVAC work. Bill is one of the original authors of the Refrigeration and Air Conditioning Technology manual. A common issue that techs have in low-voltage diagnosis is that they overcomplicate the issue. Techs should take the time to trace out the system and see where all the wires lead. The techs can be more effective if they know a system's components and those parts' relationships. During diagnosis, some techs also don't allow themselves to use their hands. Bill recommends using an alligator clip on the system as you "walk your way" through the whole circuit for diagnosis. "Short" is a commonly used term. A true "short" occurs when the current takes an undesigned path with almost no resistance. Some of the things that we casually call "shorts" are actually open-circuit issues where the current doesn't make it all the way through the circuit. Real "shorts" include shunts on the load and blown fuses. If a fuse blows but everything else in the low-voltage circuit seems to be operating fine, check the amperage at the transformer outlet. Electronic boards give techs a lot of trouble because they seem complicated. But, in the end, these boards are just switches where a hot wire goes in and a hot wire goes out. (The common wire goes straight through the board.) The board is nothing more than a distributor of voltage, and the best way to work on them is to simplify them. You can simplify electrical boards by figuring out the inputs, outputs, and sequence of operation. Bill also discusses: Grounding on one leg Connecting to ground "Probing" the hot side Measuring amperage on a thermostat "Spark-tricians" Commercial vs. residential low-voltage electronics Stripping wires If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, refrigeration tech Eric Mele talks us through some common characteristics of walk-in freezers and refrigerators. Eric recently discussed reach-in refrigerators on the podcast, and you can listen to him talk about those HERE. Common walk-in applications include coolers, freezers, and wine rooms. You may even see some package units. Condensers typically go on top of the box or the roof, and evaporators are inside the refrigerators. Many of these refrigerators also have pump down solenoids on their equipment. Thermostats mostly control the opening or closing of the solenoid valve. To cycle the unit, you shut off the liquid line and let the system pump all the refrigerant into the condenser. Evaporators tend to come in the side-discharge or pancake-style varieties. Wine rooms may also have ducted evaporators. Some older evaporators may not have fans; we call these gravity evaporators. Heaters are components that you'll see quite often on walk-in equipment. Drain pan and drain line heaters are critical for walk-in coolers, especially freezers. You can test them by touch or by using a thermal imaging camera. Freezers also have door heaters. Walk-ins also have low-ambient controls. Fan cycling is a low-ambient strategy, but commercial walk-in refrigerators may also have a headmaster. When you first start working on walk-ins, you may feel overwhelmed if you don't have all the parts on you. However, if a unit has multiple fans and only one is not working, you can typically still run the equipment if you cover the faulty fan and seal up the opening in the shroud. The goal is to get (or keep) the equipment running to save consumable products. Eric and Bryan also discuss: Pressure switches Defrost controls Troubleshooting equipment (sight glasses, etc.) Adjusting charge Superheat values Patching coils 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 some basic best practices for wire routing and wire connections in HVAC work. When it comes to electrical work of any kind, the wires must have proper protection. For example, the wires must be in the proper conduits. They must also work on appliances that they are rated for. HVAC technicians must also understand their qualifications against local codes to ensure they have been authorized for electrical work. You also NEVER want to route the wire through an opening you can't shove your finger through. If you can cut your finger on an opening, then that opening will probably cut the wire. If you need to run a wire through one of those difficult places, use a grommet. In any case, make sure you properly strap the wire, such as with zip ties. Do NOT trim wires to make them fit a connection. When routing wire, you WILL be making connections inside the appliance. Make sure you know your connectors and their ratings to make the best, safest connections possible. Check if there is any tension at the connections and disconnects; if there is tension AGAINST the terminal, check your wire angles and adjust them until they sit still or have a little tension towards the terminal. The goal of creating a good connection is to avoid melting, arcing, and other unsafe conditions. Replace melted plugs and leads entirely if you come across them. When you make a crimp connection, make sure you give them a good tug to check their tightness. Make sure there are no exposed wires by your crimp connections. Soldered connections are usually excellent connections, especially with heat shrink over them. Bryan also discusses: Using torque screwdrivers Terminal crimping (insulated terminals, indentations, using ratcheting crimpers) Lineman splice "Doubling over" If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In the second part of this podcast series, Jim covers the basics of furnace commissioning in more detail with some common-sense practices. (Listen to Part 1 HERE.) Even though installers set up a furnace system, the technicians help with the equipment startup and commissioning. That way, two parties can ensure that the installation is proper. The technician is perhaps better equipped to check the electrical connections. As technicians, we can also check the polarity of the power supplies (ensuring that the sine waves are in sync). If the polarity is backward, sometimes the hot wire has been switched with another wire, or you may have to switch the primary or secondary on the transformer. Flame rectification also ties directly into the electric components of a furnace. Inspection is also a critical component of furnace commissioning. As such, our eyes and ears will be our most important tools during the commissioning process. During the inspection, we should check over the original factory parts to ensure that everything is in order and that the furnace will operate safely. After we've calculated the temperature rise and set the blower speed, we must evaluate our static pressures. The static pressures let us know how our motors and ductwork are doing. The goal is to get our static pressures as close to 0.5" wc as possible. Be sure to perform a flame disruption test to ensure that the flame does not starve. Many technicians also fail to check the high limit cutout. When techs fail to check that cutout, the heat exchangers can break from stress. To check that high limit cutout, we can use a piece of cardboard to block the filter; that blockage raises the temperature, and it's our job to make sure that the limit cuts out and shuts the burners down. Jim also discusses: Grounding screws ECM motors Home insulation and furnace/ductwork sizing Furnace switches/safeties Flame rod microamps 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 talks about blower taps in furnace systems. He explains how to set up their fan speeds and repair them. Before you even look at the blower taps in a system, you must know a bit about the system design. Is the system supposed to remove high amounts of sensible heat? What is the capacity? How quickly should the thermostat drop? When a system is supposed to move lots of heat and has a high capacity, it needs high airflow; to run optimally, the system needs higher fan speeds to move more CFM per BTU. Moreover, a Manual J calculation can tell you how much sensible and latent heat the system must move. Also, keep in mind that system tonnage does NOT always indicate the amount of BTUs a system is actually moving. Conversely, to calculate the airflow needed for heating, you must look at temperature rise. Ideally, your temperature rise should be near the middle of the temperature-rise range. So, how do you set the airflow and know how much you're producing? That's where you measure your static pressure and look at fan tables. Remember to make sure the blower is clean and to factor in additional resistance from components like heat strips or filters. Alternatively, you can measure airflow with a duct traverse or by using an airflow hood. Then, you set the fan speed accordingly. Overall, to set the blower taps, you need to be able to measure your airflow and read fan charts. If you're merely commissioning a new system, measuring airflow becomes less important; instead, you must ensure that the manufacturer's fan charts are correct. Remember, the airflow needs to be different for a customer's heating and cooling needs. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast episode, Jim Bergmann covers furnace commissioning, including setting up furnace input, clocking the meter, setting temperature rise, and much more. The goal of commissioning is to optimize a furnace's efficiency; we want to make sure we correctly engineer the intake/exhaust system to extract as much heat from the flue gas as possible. The commissioning process for an 80% furnace is pretty similar to that of a high-efficiency furnace. Checking gas pressure, setting temperature rise, and combustion analysis are critical procedures when commissioning both furnace types. Moreover, you must know the heat content of the fuel and the amount of fuel going into the furnace before you can determine the correct input. There is an acceptable range for gas pressure, typically within 10% of the specs (usually 3.5" wc, so the acceptable range is 3.2-3.8" wc). Both the gas pressure and heat content let you know how efficiently the furnace is firing. When checking the input, you must clock the gas meter; you do that by timing a single revolution of the gas meter and determine how much fuel goes into the appliance during that time period. You can't have the water heater on at the same time that you are clocking the meter. When you clock the meter, you can start with a gas pressure of 3.5" wc and go up to 3.8" wc. When clocking the gas meter, you may realize that the orifices are incorrectly sized. Ideally, you want your temperature rise to be in the middle of the manufacturer-specified range. For example, if the range is 40-60 degrees, you would want your temperature rise to be close to 50 degrees). Jim also discusses: Weighing condensate Primary vs. secondary air Excess air Changing/resizing orifices Other gas lines in the home Ductwork sizing for temperature rise/CFM Filter considerations If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

This short podcast episode is about saturation and what it means. Bryan covers related topics, including boiling, evaporation, and condensing. Saturation refers to something that is "full" of something else. In science, "saturation" refers to a substance being in the middle of a phase change. (For example, boiling water stays at 212 degrees until it all boils off and becomes water vapor.) In HVAC, we often use the term to refer to refrigerant with liquid and vapor are present at the same time. The refrigerant is typically both liquid and vapor in the evaporator and condenser; phase changes occur in those two components as refrigerant changes from a liquid to a vapor and vice versa. Refrigerant tanks are contained systems, so the liquid-vapor mix remains at equilibrium, and the temperature and pressure will change at a predictable rate. That is why we can use the P-T chart to determine the refrigerant type; a given type of refrigerant that is changing state at a given pressure will always be a certain pressure. The process of changing state is where we can utilize so many more BTUs of heat. When a substance is at saturation, that substance will not increase in temperature so long as it remains in its current state. However, that substance will continue absorbing heat until it fully changes its state. We call the added heat that does NOT contribute to a temperature change "latent heat." Evaporators are so effective at absorbing BTUs of heat because refrigerants have relatively high latent heat of vaporization values; it takes a lot of added heat to make a refrigerant change from liquid to vapor. However, evaporation can occur WITHOUT boiling. Temperature is only the average heat content, and some faster-moving liquid molecules can still break free and become gas. If you have an iPhone subscribe to the podcast HERE and if you have an Android phone subscribe HERE.

In this discussion with Bill Spohn from TruTechtools.com, we cover the practical steps and tools for YOU to start measuring airflow today, if not sooner. There are several ways to measure airflow; when measuring airflow, start with the "why" rather than the "how." Understand what the goal of the airflow is before you begin taking measurements in random places. You can take a bulk measurement at a return, but you have to be prudent to avoid human error. The best way to avoid error is to use a TrueFlow grid, which replaces the filter and uses a pitot array to measure airflow in the return. Another relatively easy way to get a bulk measurement is to use a flow hood. However, it can be easy to mess up the positioning of a flow hood (or not have enough room for it). Many techs misuse tools like vane anemometers and collect poor data. Vane anemometers can gather information throughout the duct (mini vane) or over the supply or return (larger vane). You want to pick up the micro-transitions in air velocity to get quality data; you can use either point or traverse measurements and average those readings to come up with your average CFM. We can take measurements INSIDE the duct with pitot tubes (although we have our reservations about using those), hot wire anemometers, and mini vane anemometers. In-duct measurements require multiple measurements and consistency during testing. A common system airflow measurement doesn't measure CFM at all; that measurement would be static pressure. However, you need to have the correct tables and understand all of the load requirements to measure static pressure effectively. Bill and Bryan also discuss: Pitot tubes vs. static pressure probes Air movement metaphors Point vs. traverse measurements Static pressure drop Total system airflow setup Ventilation airflow If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Today, Bryan discusses delta T (evaporator air temperature split) what it is, what it means, and how to avoid some common pitfalls. Delta T is NOT the air temperature rise on a furnace, and it is NOT the design temperature difference (DTD). Instead, delta T refers to the temperature split between return air entering the evaporator coil and the supply air leaving the unit. Typically, 20 degrees (Fahrenheit) is a desirable split, but there is still a range based on relative humidity, enthalpy, and airflow. The range can be as high as 24 degrees. To measure delta T properly, you need high-quality probes. (Don't use cheap dial probes if you don't want an inaccurate measurement.) Whenever you expose a probe to another probe via an air gap, they can affect each other's temperatures. Radiant heat transfer occurs between them, and you can get incorrect readings. In general, you want to keep your supply probe downstream of the coil. Do NOT use an infrared thermometer to measure the temperature split. Infrared thermometers are inaccurate and may also pick up duct gains. Delta T is not a fixed value, but it is still rather predictable. You can use our calculator to help get an idea of the measurement you're aiming for. Some factors that reduce the temperature split include high airflow, high relative humidity, and low capacity (and all of its possible causes). High temperature splits typically occur due to poor airflow. Dirty filters and coils are the main culprits of poor airflow and high temperature splits by extension. Dehumidification mode and lower relative humidity may also result in higher delta T values. (However, dehumidification mode is usually intentional and is rarely a cause for concern.) If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this simultaneously heavy and lighthearted discussion, Bryan Orr and Andrew Greaves discuss ego, Dunning-Kruger, insecurity, and apprenticeship in the trades. In the early days, apprenticeships were quite different from the way they are today. One-on-one mentorship used to be a much more significant component of early apprenticeships, but that style of training is uncommon for today's apprentices in all sorts of trades. As a result, many young technicians enter the field too quickly and don't have the training to perform a job skillfully. As such, many inexperienced techs become confident with bare-minimum work because nobody points out their mistakes. Moreover, many green techs also don't have the self-awareness to recognize their lack of skill. We call that disconnect between confidence and skill the "Dunning-Kruger effect." Another common scenario is when techs understand that they don't know something but are too embarrassed to admit it. Unfortunately, a tech's ego can get in the way and make them stick to their guns for no good purpose. However, old-timers are also part of the ego-ignorance equation. Many of them fail to explain the "why" behind their practices. Some old-timers share bad practices without knowing what they're doing. Moreover, when leadership breeds a culture of ignorance, the younger technicians will be set up for ignorance and ego problems. The way to move past the Dunning-Kruger effect and check your ego is to think about what you're thinking about. Question the validity of your OWN thoughts and ideas, and accept that you could be wrong or have a flawed understanding. Bryan and Andrew also discuss: Techs' behavior on social media Cognitive bias Metacognition Organizations that breed ignorance and ego issues Check out AK HVAC on YouTube - https://www.youtube.com/user/akgreaves If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short episode, we review the basics of the refrigerant circuit. The standard HVAC refrigeration circuit has four main components: compressor, condenser, metering device, and evaporator. The compressor squeezes refrigerant vapor into a smaller volume by applying lots of pressure. It simultaneously moves and compresses gaseous refrigerant. The more a compressor has to compress a gas, the less gas it moves. The more gas a compressor moves, the less gas it compresses. Then, the refrigerant leaves the compressor via the discharge line. The discharge line is very hot because the temperature increases with pressure. The hot vapor feeds into the top of the condenser. The condenser brings the gaseous refrigerant back down to a liquid. Condensers come in all shapes for various applications, but all condensers' main goal is heat exchange. Condensers desuperheat, fully condense (change vapor to liquid), and subcool. Subcooled liquid refrigerant leaves the bottom of the condenser via the liquid line. The liquid line leads warm, subcooled liquid refrigerant to the metering device. The metering device's goal is to drop the refrigerant's pressure. That pressure drop facilitates boiling in the evaporator coil. The evaporator absorbs heat from the space. Fans blow warm air over the coils, allowing that heat to come into contact with the refrigerant. The refrigerant boils when it absorbs enough heat. The last few rows of the evaporator are where superheating occurs. Superheat is the temperature above the saturation point; superheat indicates that the refrigerant is all vapor, no longer a liquid-vapor mix. Then, the vapor refrigerant travels back to the compressor via the suction line; the refrigerant circuit restarts. The suction line is rather cool; we use some of that cool refrigerant gas to cool down the compressor. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jon Bennert from Air Oasis teaches us about PCO and Bi-Polar air purification and how it improves indoor air quality through ionization. Photocatalytic oxidation (PCO) is a technology field that uses catalyst metals, hydration agents, and lights to help remove pollutants from the air. These technologies shine a light source on a photocatalyst metal that reacts with pollutants in the air. These pollutants include volatile organic compounds (VOCs), viruses, mold, and other unwanted particles in the home. Some bacteria that are good for you in your gut are NOT good in your respiratory system. Bi-polar ionization causes reactions to occur with the pollutants. Ionization could potentially break down molecules or genetic material in VOCs and viruses, respectively. Other biological contaminants, including mold and bacteria, also have their proteins broken down and become unable to replicate or reproduce. Larger particles, like dust, are forced to clump together and become so heavy that they fall out of the air. The air motion in the Bi-Polar product line is the mixture of positive and negative ions that are splitting water vapor molecules. So, you can tell if the Bi-Polar products are working if you can feel airflow; you can tell that the product is generating ions. These ions work to break down harmful particulates in the air AND eliminate odors. Bi-Polar products that use ionization are desirable for people with allergies or homes with lots of shedding pets. Bi-Polar products are small and easy to install. They simply fasten to the shroud with magnets. These products also come in some voltage ranges, and they have a small energy footprint as well. Jon also discusses: Ionization history Petri dish tests Bi-Polar products and PCO usage Outdoor air standard qualifications Servicing Bi-Polar products Ice machine contamination 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 comes on to talk about reach-in coolers (refrigerators), freezers, and wine coolers with some mindset and technical tips. We mostly discuss self-contained equipment. Coolers are medium-temperature applications, while freezers are low-temperature applications. Wine coolers vary from normal coolers because they have slightly higher temperatures and controlled humidity. The cooler must control humidity to preserve the wine quality and prevent the cork from swelling. Metering devices vary with the size and type of equipment. We typically see capillary tubes in smaller reach-in coolers and TXV in larger ones and blast chillers. We typically use automatic expansion valves (AEVs/AXVs) for wine coolers. An AEV controls suction pressure in conjunction with a TXV, which controls superheat. Hooking up gauges is typically a last resort. We can chalk up most reach-in cooler problems to restrictions, which usually indicate cleanliness issues that are easy to solve. For example, dirty condenser coils can cause cap tube restrictions. Control strategies vary by size, application, and complexity. For example, simple reach-ins rely on manual defrost only. However, even higher-end blast-chillers recommend manual de-icing (although they DO have defrost controls). The main defrost types are manual, fan, and electric. Smaller reach-ins have a "cold control." Cold controls are relatively simple dials that stop the compressor when the evaporator coil reaches a set temperature. Most reach-in refrigerators are ONLY intended to hold products at temperature. With the exception of blast chillers, most reach-ins cannot bring a bunch of hot food down to temperature. These situations will result in poor performance, so customers should be aware of the refrigerator's appropriate usage. Eric also discusses: The troubles of charging reach-in cases Creating your own access ports Electric defrost in reach-in applications Thermal imaging cameras in diagnosis Manual defrost strategies Pump down Check out Eric Mele on YouTube HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Stephen Rardon and Neil Comparetto join the podcast to talk about their headfirst dive into building performance as HVAC techs. They discuss jobs they do, how the transition has been, and important HVAC principles in building performance. Addressing duct leakage can help with indoor air quality and home performance overall, but it can also even help reduce noise. Building performance and HVAC both require the serviceperson to give the customer options and inform them of their specific situation. In both cases, you would give the customer a chance to improve their living situation by offering a personalized set of offerings. However, building performance allows us to give the customer control over their comfort. The main selling points of building performance solutions are health, comfort, and efficiency. Customer health is important because they want to make sure asthma, allergies, and other conditions won't be aggravated in their home. Comfort is important for many people, and efficiency is typically important for those with a green ethos. If contractors and technicians want to get into building performance, it pays to take time to learn the business. It's even better if contractors put training programs together for their technicians. However, technicians need to be able to care about the material; otherwise, the investment in training may not be worth it. You must care about why we need building performance before you enter that side of the industry. Stephen, Neil, and Bryan also discuss: Bringing building performance into HVAC business Blower door testing Sales packages System performance inspection Challenges of growing a company Precision manometers and other building performance tools Zonal pressure diagnostics Creating service departments within companies Thinking of the building as a system Expertise to combat automation If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Dick Wirz, author of Commercial Refrigeration for Air Conditioning Technicians, talks to us about refrigerator and freezer defrost strategies. Check out Dick's book HERE. In commercial refrigeration, we deal with much lower evaporator temperatures than residential HVAC. Although an evaporator temperature of 40°F may be commonplace in residential HVAC, you can expect evaporator temperatures from 25-30°F in refrigeration. Even though having ice on the coil is a negative thing in residential HVAC, it is perfectly normal in refrigeration. The purpose of defrosting is to bring the evaporator temperature above freezing to melt off the frost. We can defrost a coil in a few different ways, including a mere off-cycle defrost in medium-temperature refrigeration. When the system shuts off, the evaporator coil can start defrosting. However, if too much heat is introduced to the system, more frost can accumulate on the evaporator coil. As such, a planned defrost may be in order. These defrosts occur on a timer and turn the system off overnight. Alternatively, these defrosts may use electricity or hot gas to remove ice from the coil more rapidly, especially in low-temperature applications. Electric and hot gas defrost are common defrost types. The hot gas method generally reverses refrigerant as a heat pump does; hot discharge gas runs through the evaporator coil and melts the ice off the coil. However, hot gas is an expensive method and can negatively impact system longevity if used improperly. The electric method is cheaper than the hot gas method; this method relies on electric heat outside the coil to melt the frost from the outside. Dick also talks about: Warm air infiltration Coil-sensing thermostat controls Defrost failsafe Defrost termination "Snowing" in the box and fan delays Drain pan heaters and drain complications Paragon timers Demand defrost setups/clocks Check out RefTech HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, Bill and Bryan recap the 2018 AHR conference with what they learned and what you can expect to see in the HVAC/R trade in the next year. There were 2100 exhibitors who gave demonstrations and discussed products. AHR shows the real scope of the HVAC/R industry, and it is an excellent opportunity to learn more about the trade and do some networking. At the AHR conference, there were some demonstrations that may indicate a paradigm shift in the industry's best practices. For example, the AccuTools booth projected the rate of evacuation through three hoses of different diameters, including the mythical 1" hose. The visual representation of those evacuation rates showed the trend towards faster evacuations with larger hoses. More tool manufacturers may jump on the trend to make larger hoses that assist technicians and lead to better evacuations. The technology on display at AHR also testified to the fact that many more tools are integrating with our cell phones, including the CPS IAQ monitor. AHR also had a treasure trove of new technologies, including BluVac's Bluetooth-connected combustion analyzer. BluVac's branding is very science and engineering-focused, and they also fine-tune their technology to support techs in the field. Overall, AHR was a fantastic forum for people to spread information about products. In turn, Bill and Bryan had some of their product research validated and built upon. Bill and Bryan also discuss: Attaching micron gauges at the pump Professional branding Industry education Surge suppressors and melting issues The time Bill called Bryan out Engagement with HVAC educational materials Testo precision manometers and additional heads Filling the HVAC/R skills gap Increasing your value as an individual technician in this industry Building performance in the HVAC industry Internet of things (IoT) The commercial HVAC market If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast episode, Bryan talks to west-coast commercial tech Jim Loring about pneumatic controls and variable air volume (VAV) systems. People sometimes confuse pneumatics and hydraulics. Hydraulics use liquid to provide pressure; conversely, pneumatics use air to provide pressure. Pneumatic controls use a bit more energy than other controls, but they are less costly all around. Nowadays, direct digital controls (DDCs) provide greater energy savings than pneumatics. However, pneumatic controls were a precursor to the DDC technologies we use on actuators today, and they are still a prevalent technology. The air compressor is a critical component of pneumatic controls. That is because pneumatic controls require clean, dry air. Air compressors have an auto-drain and auto-dryer to help purify the air for peak performance. However, while air compressors are basic, their maintenance practices are often overlooked. Variable air volume (VAV) units vary airflow throughout the building via zones. Each zone has a damper and a thermostat. The thermostats control the dampers, which control airflow to the zone and move via actuators. In a pneumatic control system, the air pressure release or gain at the thermostat moves the dampers. Thermostats also have to bleed off some of that air via direct or reverse-acting controls. Bypasses help regulate static pressure when dampers close. Thermostats can help modulate the dampers; they don't merely open and close. The modulation occurs within a certain pressure range on a VAV system. (For example, 8 PSI would close the damper while 13 PSI would leave the damper wide open.) In addition to damper modulation, velocity controllers help control the air velocity based on signals from the thermostat. Jim also covers: Common air compressor problems Pressure-reducing valves (PRV) Restrictor tees Direct-acting vs. reverse-acting controls Heating and cooling in VAV systems Damper position If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jeremy Smith goes over floating suction and floating head refrigeration strategies. He also talks a bit more about low-ambient equipment operation. Floating suction controls developed when we started using low-pressure controls on rack refrigeration. As the electronics advanced, we developed controls that could control temperature, which impacts pressure as well. Nowadays, controls can cross data and be much more effective at controlling pressure and temperature. Suction pressure is the greatest contributor to a system's compression ratio. The higher the compression ratio, the less efficient a system is; a high compression ratio can be costly for grocery business owners or managers. Therefore, floating suction controls set the temperature exactly to what it should be based on the system's load, not lower than what the suction temperature should be. Floating head controls attempt to minimize the compression ratio from the high side of the system. The floating head attempts to maintain head pressure by matching condenser fans closely with ambient temperatures. Ambient temperature controls the floating head control's set points. These floating head controls can set the condensing temperature as low as 68 degrees (F). The main factor that prevents the temperature from getting any lower is the expansion valve. It is possible that EEV usage could enable even lower temperatures, but they have been quite problematic so far. Jeremy recommends taking advantage of natural subcooling to get the most out of your floating head strategy. These controls have to decrease capacity before they hit their targets. As such, these floating head and suction controls can be erratic and "swing" from extremes upon startup. Jeremy also covers: Energy and monetary savings Pressure differentials caused by floating head controls Expansion valves in refrigeration Superheat "floating" "Drain" leg or regulator If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Bryan talks with Jesse and Nathan about setting up dehumidification for residential equipment in general. They also discuss some of the required and recommended settings on an Ecobee thermostat. On typical single-stage residential equipment, dehumidification works based on CFM per ton. We control humidity by dropping the CFM across the indoor coil and extending runtime. However, as you cool the air, you reduce its ability to hold moisture. So, you increase relative humidity through cooling. When we have achieved the desired humidity but not the desired temperature, the thermostat reduces the fan speed. Thermostats should vary the fan speed based on the call for cooling and the humidity in the air. Some systems have a dehumidification terminal; when there is a call on that terminal, the fan speed gets maxed out. Some older thermostats would display relative humidity but did not have a dehumidification terminal; these systems would merely overcool instead of removing the humidity. These systems would be very prone to freezing. Nowadays, freezing still occurs on occasion, but our newer thermostats can control their CFM per ton much better to prevent freezing. Ecobee thermostats work to integrate many different accessories. So, Ecobee thermostats try to solve every problem on a system, even on systems with supplementary humidifiers or dehumidifiers. These thermostats don't have a dehumidification terminal, but they have ACC- and ACC+ terminals for accessories, including dehumidifiers. Many technicians become confused when they think that the fan is a core element of dehumidification. Instead, the ACC terminals should be set as single-transformer, and you can choose the dehumidification option (which should NOT have the fan on). When wiring the Ecobee for dehumidification, connect the DH terminal to ACC+, remove the jumpers, set up the single-power source, do NOT dehumidify with a fan, and set "Dehumidifier Active" to "Open." If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, we cover the skills and traits needed to be the best residential service techs you can be. We follow up on the last episode's tips for getting a raise and discuss how to become more valuable as an employee. All good service techs clearly have to be able to repair and maintain systems well. Commercial and residential techs need to demonstrate mechanical aptitude. However, soft skills are what separate the good residential service techs from the excellent techs. Observational skills are imperative. Residential techs need to take a wide-narrow-wide approach to diagnosis. They must also utilize their senses to observe the ENTIRE piece of equipment. Observant techs are quite good at catching potential issues before they spiral out of control. Resourceful techs make the most of the books, manuals, and other resources they have. If they don't have a resource, they find it. Since residential service techs deal with customers, it pays for them to be pleasant with people. These people are still honest with customers, but they're positive and empathetic. The best techs are organized and keep their tools in order for maximum efficiency. Efficient techs increase their value as employees with every task. They become quicker as they become more confident with tasks. Great techs are also conscientious. They are aware of their surroundings and considerate of the customer's property and feelings. Excellent techs are also self-aware about their knowledge. They understand that they don't know everything, and they know what they have to study or search for. Finally, the best techs are all neat, clean, and communicative. Residential service techs are our industry's ambassadors, and it is important that they communicate well AND project a good image of the industry and company to the customer. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

As we ring in the new year, this episode focuses on how people in the HVAC/R trade can get a raise, promotion, or bonus without facing rejection or sounding selfish. Before you think about asking for a raise or promotion, evaluate your company. Is your company pragmatic? Does the company refuse to address conflict or let tempers run high? Do your leaders care about making decisions logically and promote people who will truly help the business? A pragmatic company makes logical decisions and respects the employees who keep the business alive. Many people want to ask for a raise when they find out that someone earns more than them or feel as though they haven't had a review in a while. People in these situations feel as though they are OWED additional pay. Here's Bryan's advice: DON'T ask for a raise, promotion, or bonus unless you have a written salary agreement that hasn't come to fruition. When you ask a leader for a raise, you make your leaders put their guard up. In general, it's not a good idea to make someone else put their guard up when communicating with them. If you want to talk to a leader about a plan to earn more money in the future, try to explain your vision of the future for the company; solve a company problem, or contribute to a leader's solution. Avoid self-assessments; talk about a plan or vision where YOU play an integral part in improving the company. Tie YOUR pay to the company's success, whether your solution addresses revenue, callbacks, or training within the organization. Overall, you have to show that you're willing to accomplish a task to earn more pay. A pragmatic business will see the value in your ideas and will be more willing to give you a raise, promotion, or bonus after you execute your plan. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast episode, we discuss power distribution and some practical tips about three-phase, single-phase, and split-phase power. The power company generates three-phase power; a power pole transformer typically has three current-carrying conductors. Each phase of power runs at 60 Hz and generates a sine wave. That sine wave peaks and valleys in a wavy formation. Power is generated in a rotating magnetic field, so it is helpful to think of a sine wave as a variation of a circle. Transformers take high voltage and bring it down to 120V split-phase via a winding on the left, a winding on the right, and a neutral tap. The split sine waves are exactly 180 degrees out of phase; they are direct opposites, and they will intersect and both be "off" at the same time. The center is neutral. This 120V split-phase power results in 240V total; therefore, we can use them in 240V applications. Split single-phase motors require a capacitor. Three-phase power uses all three legs of power, and the sine waves are 120 degrees out of phase with each other. In three-phase power, only one wave will be "off" at any point in time. Three-phase power is a more efficient means of running motors; split single-phase power is relatively inefficient and requires a capacitor. However, reverse-phasing is a possibility and may run motors backward, causing damage. The most common type of three-phase transformer uses the wye configuration and works for 208V applications. Bryan also discusses: Wye vs. delta configuration Delta configuration high leg Start assistance and capacitors Residential vs. commercial applications Capacitor failure 277V and 480V applications Replacing single-phase with three-phase power or vice versa Three-phase condensers with single-phase air handlers If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Learn about large-scale desiccant dehumidification from the expert, Tom Peterson. Tom works with CDI (Climate By Design International). Dehumidification has several different methods and applications. Cooling is the most basic of those methods, but it has its limitations. For example, dehumidification by cooling may leave moisture on the coil and lead to freezing. Desiccant dehumidification can remove water from the air without the possibility of freezing the unit. Desiccants are crystalline structures with pores, and they remove moisture via adsorption. Water has a pressure that pushes other water molecules into those pores. Partial pressures also help force the pressures from high to low. Moisture will only come out of the desiccant upon heating the air around it. Heat excites the water molecule that has been trapped in the desiccant pore, so that molecule breaks the bond between itself and the desiccant (desorption). Commercial/industrial dehumidifiers make use of desiccants. Desiccants fit into rotors or wheels, and air passes through the desiccant rotor. The goal is to dehumidify and only dehumidify. So, no heat transfer occurs as air passes through those desiccant rotors. About 3/4 of the rotor works to adsorb moisture, and about 1/4 of the rotor works to desorb moisture. We measure moisture in a unit of weight called grains per pound of dry air (simplified to "grains"). Grains refer to moisture rather than a humidity percentage, but grains and humidity are indeed linked. Even though we attempt to reduce grains per dry air, we cannot have negative grains of moisture; it is an impossibility. Tom also discusses: Sensible vs. latent heat Grain depression Dew point Learn more about desiccants at the CDI website at cdihvac.com and their YouTube channel HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Carter tells us why compression ratio is important, what it means, why it changes so much on heat pump systems, and the effect it has on system operation. We also talk a bit more about heat pumps and their unique challenges beyond compression ratio. Compression ratio is a comparison of discharge pressure to suction pressure. A ratio of 3:1 indicates that the discharge pressure is three times higher than the suction pressure. The higher the pressure difference, the less gas you move and the less efficient your system is. The compressor has a fixed volume, but the gas's actual mass varies based on density and pressure. So, lower suction pressure results in less gas being moved. Dirty filters, coils, and other means of clogging the system can drastically increase the compression ratio. Heat pumps are especially sensitive to compression ratio changes because they move varying amounts of refrigerant depending on the operating mode. As such, charging heat pumps can be a challenge. Some heat pump manufacturers use a charge compensator to help make charging a slightly less difficult task. Heat pumps may also have coils with smaller surface areas, which can drive up the compression ratio. Heat pumps have highly variable evaporator temperatures, and refrigeration systems have highly variable condensing temperatures. Both of these highly variable conditions may indicate systems with susceptibility to high compression ratios. In the case of refrigeration systems, the metering devices are critical components for reducing keeping the compression ratios at bay. If you cannot find manufacturer literature or are working on an old heat pump, Carter recommends using airflow and temperature difference to determine how much heating the system is accomplishing. Carter and Bryan also discuss: Rheem and Ruud heat pumps Centrifugal blowers Plenum placement New inverter-driven compressors If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In today's podcast, Bryan talks about voltage (volts) and resistance (ohms), specifically using a voltmeter and an ohmmeter for diagnosis. We also discuss voltage drop. In many cases, Ohm's law is impractical for field usage because of the additional resistance from inductive reactance. We also don't typically measure impedance and only care about resistance on the windings. However, Ohm's law is still a valuable concept because it teaches technicians the relationship between voltage, amperage, and resistance (ohms). Ohm's law states that volts equal amps multiplied by ohms (E = I x R). Therefore, if the volts stay constant, ohms will increase as amps decrease and vice versa. We distinguish lines from loads in circuits; we say that loads are the parts that "do" something due to resistance in a circuit. There are two kinds of loads: inductive and resistive. Inductive loads generate expanding/collapsing magnetic fields, which can also cause rotational force or activate a solenoid. Resistive loads generate light and heat, so heat and resistance are related. Of course, the diagnostic tools we use (multimeters, voltmeters, ammeters, ohmmeters, etc.) also have their limitations. A voltmeter merely determines a difference in charges between two points. When using a voltmeter on a low-voltage circuit, try to plant one of your leads on the common side and take readings throughout the circuit with your hot lead. Ground is also NOT a reliable reference point for diagnosis. The point of measurements is to prove what we suspect to be true; we must understand what our data mean for system operation and what our tools' diagnostic limitations are. For example, when we ohm out contactors, we check to see if they're open. Bryan also discusses: Fixed wattage or resistance Reading between wires Meter lead placement Amperage (dynamic current/electrons) Undiagnosed shorted circuits Contact points Voltage drop and resistance Infinite ohms Wire length If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

Jamie Kitchen from Danfoss talks all about variable-speed motor technology. He discusses why those motors exist, what they do, and how to think differently about the future of HVAC/R. Most techs think about variable-speed motors as the X13 and ECM blowers in residential applications. Those motors can adjust their performance based on ambient temperatures and moisture levels. So, variable performance may result in better comfort and efficiency. ECM motors adjust airflow based on sensor inputs, especially dehumidification calls. The sensors may pick up both sensible and latent heat content. Sensible heat is what we can feel (dry-bulb temperature). Latent heat refers to moisture in the air (humidity, wet-bulb). ECM motors adjust their speed based on data from both, which is highly beneficial for greater comfort in the home. Human comfort is a lot more complex than feeling satisfied with a single number on the thermostat; ECM motors help control humidity and give you more leeway over selecting an acceptable dry-bulb temperature of a space. Variable-speed motors exist on the commercial side of the HVAC industry as well. Commercial HVAC equipment brings in more fresh air and is overall less restrictive than residential. A variable-speed motor can help manage the latent heat of fresh air and work as a form of air treatment. Variable-speed motors compare indoor and outdoor conditions to treat the fresh air and maintain the indoor conditions. These motors account for sensible and latent heat loads, just like the residential ECM motors, and they adjust themselves constantly. Jamie and Bryan also discuss: Capacity and heat profiles X13 motor controversy Having multiple variable-speed components in a system (compressor, blower, etc.) Sensible heat ratio (SHR) and heat load matching Complex human comfort Reheat coils Air treatment requirements If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.