HVAC School - For Techs, By Techs

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

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

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

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

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

In today's podcast episode, Jonathan Romberg comes on to discuss how the Danfoss ERC 213 works and reviews its parameters with us. Timestamps: 10:30 – Key Features 10:41 – Voltage Protection 10:56 – Compressor Protection 14:43 – Applications 15:15 – App 0 No predefined application 15:28 – App 1 Medium temperature ventilated refrigeration units with timed natural defrost 15:52 – App 2 Medium temperature ventilated refrigeration units with timed electrical defrost 16:03 – App 3 Low temperature ventilated refrigeration units with timed electrical defrost 16:13 – App 4 Medium temperature ventilated refrigeration units with electrical defrost (by temperature) 16:26 – App 5 Low temperature ventilated refrigeration units with electrical defrost (by temperature) 16:37 – App 6 No predefined application with a simplified list of parameters 19:45 – Sensors 22:06 – Basic Groups of Parameters 23:09 – r-- Thermostat 23:12 – r00 Temperature setpoint 23:24 – r01 Differential 23:32 – r02 Min setpoint limitation and r03 Max setpoint limitation 24:02 – r04 Display offset 25:19 – r05 Display Unit (°C/°F) 25:33 – r09 Calibration of Sair 25:47 – r12 Main switch 27:17 – r13 Night set back 27:48 – r40 Thermostat reference displacement (offset temperature) 28:30 – r96 Pull-down duration and r97 Pull-down limit temperature 29:06 – A-- Alarms 29:13 – A03 Delay for temperature alarm during normal conditions 30:15 – A12 Delay for temperature alarm during pull-down/start-up/defrost 31:00 – A13 High-temperature alarm limit (Cabinet/Room) 31:34 – A14 Low-temperature alarm limit 31:55 – A27 DI1 delay and A28 DI2 delay 32:17 – A37 Condenser high alarm limit 32:41 – A54 Condenser high block limit 33:45 – A72 Voltage protection enable 34:03 – A73 Minimum cut-in voltage and A74 Minimum cut-out voltage 35:04 – A75 Maximum Voltage 37:37 – d-- Defrost 37:49 – d01 Defrost method 38:32 – d02 Defrost stop temperature 38:50 – d10 Defrost stop sensor 40:51 – d03 Defrost interval 41:16 – d04 Max defrost time 43:38 – d05 Defrost delay at power up (or DI signal) 44:29 – d06 Drip delay 44:49 – d07 Fan delay after defrost 45:49 – d08 Fan start temperature after defrost 47:21 – d09 Fan during defrost 47:40 – d10 Defrost stop sensor (part II) 48:16 – d18 Compressor accumulated runtime to start defrost 50:04 – d19 Defrost on demand 53:26 – d30 Defrost delay after pull-down 53:53 – F-- Fan control 54:03 – F01 Fan at compressor cutout 55:00 – F04 Fan stop evaporator temperature 55:51 – F07 Fan ON cycle and F08 Fan OFF cycle 56:28 – c-- Compressor 56:37 – c01 Compressor minimum ON time 56:47 – c02 Compressor minimum OFF time 57:01 – c04 Compressor OFF delay at door open 57:51 – c70 Zero crossing selection 58:22 – o-- Others 58:37 – o01 Delay of outputs at startup 59:11 – o02 DI1 configuration 1:01:36 – o05 Password 1:02:08 – o06 Sensor type selection 1:02:27 – 015 Display resolution 1:03:31 – o23 Relay 1 counter, o24 Relay 2 counter, and 025 o24 Relay 3 counter 1:04:13 – o37 DI2 configuration 1:04:52 – o61 DI2 configuration 1:05:07 – o67 Save settings as factory 1:05:39 – o71 DO2 config 1:06:23 – o91 Display at defrost 1:07:04 – P-- Polarity 1:07:06 – P73 DI1 input polarity and P74 DI2 input polarity 1:07:32 – P75 Invert alarm relay 1:07:59 – P76 Keyboard lock enable 1:08:21 – u-- Readouts 1:08:30 – u00 Controller Status 1:09:37 – u01 Air temperature (Sair) 1:10:12 – u58 Compressor relay status, u59 Fan relay status, u60 Defrost relay status, and u63 Light relay status Find out more about the Danfoss ERC 213 HERE. Learn more about Refrigeration Technologies at refrigtech.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this podcast, we discuss the real significance of superheat and why it is much more than "a way to set the refrigerant charge on a fixed metering device." Superheat is the temperature of a vapor above saturation. Many people use it to set the charge on a piston or fixed orifice, but that's not its only purpose. Superheat is a much more important reading than that, and you can take that measurement at a few different places. For example, most of us measure it outside. However, to determine how the system is feeding the evaporator coil, we would take superheat at the evaporator outlet (6-14 degrees is normal for a TXV). However, superheat matters regardless of the metering device type. Zero superheat indicates that the refrigerant is still at saturation; it is in a mixed state, not entirely vapor. So, we know that we are "overfeeding" the evaporator coil. The boiling process does not finish in the evaporator; it continues into the suction line. Overfeeding is a problem because our evaporator might not boil off all the refrigerant, and we could send liquid to the compressor. The system may be overcharged, or the evaporator load may be too low. Excessive superheat indicates that the refrigerant is boiling off too quickly in the evaporator coil. In those cases, we are starving or underfeeding the evaporator coil. The boiling process ends too early in the evaporator coil. The system may be undercharged or have too much load on the evaporator coil. When our superheat is within the proper range, we are feeding the evaporator coil correctly. The majority of that evaporator coil is being fed with boiling refrigerant. Learn more about Refrigeration Technologies at refrigtech.com. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

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

In today's podcast, Jon Bennert with Air Oasis talks about photo-catalytic oxidation (PCO) air purification. He explains how it works and what it does. The NANO products are PCO-type technologies. These technologies were initially developed for NASA storage systems on the International Space Station. Photo-catalytic oxidation (PCO) products work to reduce or sterilize pollutants or organisms in the air by using light. Sunlight produces UV rays that can kill nasty germs in the air; PCO products work similarly and may have UV lamps or not. (NANO units use UV lighting.) The UV isn't all that effective by itself. However, UV light can produce pollutant-fighting ions when the UV hits the coating within the air purifier. These ions are typically hydroxyl ions, which are more effective than ozone but don't last very long. So, PCO products are most effective when they have a large surface area with the catalyst. You can get all sorts of bacteria, yeast, and fungi inside a home. Humidity will usually only make those worse. Not to mention, you also have VOCs from cleaners and building materials, which may smell nice but greatly reduce your air quality. Humans also create plenty of pollution through humidity and dead skin cells. Air purifiers can help you deal with all of these air quality reducers. The NANO is unique, as it can run only when the fan is on and reduce ozone byproducts in your ductwork. Bryan and Jon also cover: UV lighting in the ductwork Simple organisms vs. complex organisms and defense mechanisms Ozone and ozone-generating equipment PCO byproducts and efforts to reduce those NANO sizing How Air Oasis tests the product's cycles NANO vs. competitors Improvements to the NANO over time How techs can recommend and sell IAQ products more effectively Air quality testing Find out more about Air Oasis at airoasis.com. Check out Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this episode, we talk about air as a form of matter. We cover air volume, density, weight, and mass and why it matters to you. So, air has weight and takes up space. When we measure air, we typically measure it by volume (CFM or cubic feet per minute). When we say that air takes up space, we are referring to air volume. A cubic foot of air is equivalent to a 1'x1'x1' box of air. When we measure CFM, we measure how many boxes of air we move per minute. We usually want around 400 CFM per ton, though the exact number varies by system, function, and ambient conditions. Lower CFM per ton is better for moisture (latent heat) removal, while higher CFM per ton is better for sensible heat removal. Air also has weight. When we are at higher altitudes, the air is thinner and less dense. Therefore, the air has less weight. Standard air weighs about 0.75 pounds per cubic foot (box of air). If you multiply the 400 CFM per ton standard by the standard air weight, you get 30 pounds of air per minute. That pounds-per-minute value is what we call the mass flow rate. The air density affects mass flow rate; temperature and relative humidity can change the density of air. So, the volume is the box, but density (which affects mass) is what's in the box. Even though our goal is to move pounds of refrigerant (mass), we care about CFM (volume) because fans move air regardless of density. The blower affects the CFM, but the mass flow rate is more important to the coil. We have to adjust our volume flow rate to achieve a proper mass flow rate. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.