HVAC School - For Techs, By Techs

In this live podcast from the Castbox app, we talk about analog vs. digital, digital vs. probes, and probe vs. non-invasive testing of A/C and refrigeration. We also talk about apps and various Bluetooth tools. Although analog gauges are old, reliable tools, digital gauges tend to be a bit more accurate than analog ones. However, the jury is still out on which one has the durability edge. Digital gauges also have batteries to worry about, whereas analog ones don't. Ultimately, the only reason to use analog gauges over digital ones is a personal preference. Probes work well with hoses, tees, and core depressors. We still use manifolds to this day because they have charging tees and are easy to use, though you can modify probes to make them more user-friendly. Refrigerant can be left over in the hoses, and refrigerant mixing is a possibility. Probes minimize the losses of manifolds. However, non-invasive testing is another manifold-free route. The key to using non-invasive testing effectively is to become a master of the obvious and not to put too much focus on the readings alone. While it is important to know the measurements, it is even more important to use your senses to look for clear problems. When you use tools that connect to electronics via Bluetooth, we recommend using a separate device, not your personal phone. For example, Bryan uses an iPad with a data plan. We also discuss: Five Pillars of HVAC Diagnosis Favorite temperature clamps K-type thermocouples Mandating vs. recommending tools Scales Fieldpiece probes for A/C Sporlan probes for refrigeration Advantages and disadvantages of Testo probes Core depressors Checking light commercial systems with probes Rub-outs When readings are overrated Best practices "Negative" superheat and subcooling   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan talks about ambient CO. He also explains why it matters and what you do to check for it. CO, carbon monoxide, is a colorless, odorless, and toxic gas that can result in death. It should not be confused with CO2, carbon dioxide. Although our bodies inhale oxygen and not carbon dioxide, the latter isn't toxic if it gets into our bloodstream. CO, on the other hand, displaces oxygen, which proves deadly. Carbon monoxide can also build up in your bloodstream over time, so you want to avoid repeated exposure. In some locations, you can expect some degree of ambient CO. For example, lots of car exhaust in busy cities can lead to a low amount of carbon monoxide in the air (a few parts per million). Most CO monitors detect much higher concentrations of carbon monoxide (around 100 parts per million). When working in a place where carbon monoxide is a concern, such as in a home with gas appliances, be sure to use your instrumentation to measure CO in an occupied space. Also, check for carbon monoxide spilling out of the unit. Don't confuse ambient CO with the carbon monoxide found in combustion analysis; they are NOT the same. Ambient CO indicates a bigger problem like backdrafting. Unlike standard CO monitors, you will want to use a personal ambient CO monitor that can measure down to 1 part per million for YOUR safety. Again, do NOT use combustion analyzers for personal protection! You can also offer higher-quality CO monitor/alarm suggestions to your customers.   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, Michael Housh joins us to discuss his years of experience with geothermal heat pumps and their special considerations. "Geothermal" is a rather generic term, similar to how people say "Freon" to refer to any kind of refrigerant. Those heat pumps don't necessarily have to be underground; you can have water-source heat pumps in ponds or wells, and there are also ground-source heat pumps. The ground provides a steady temperature under many conditions, which helps heat pumps work effectively in cold climates. Like other heat pump systems, geothermal pumps come in split or package types. The pump may be either integrated with the equipment or separated from it. When the equipment is separate, multiple units can use the same loop (for example, a 10-ton loop can have five 2-ton units attached). Michael designs geothermal systems. He uses software to design systems, particularly closed-loop systems, and load calculations play an important part in informing his designs. Many contractors use rules of thumb to help size the loops, but the only way to know what you're doing is to take load calculations, especially on water-source pumps. Undersizing loops can severely reduce the system capacity and make it hard to maintain temperature. To keep performance up, we also need to flush heat exchangers as part of regular maintenance. However, restrictions and contamination tend to be relatively uncommon except in pump-and-dump systems. As with any type of equipment, be sure to follow the manufacturer's recommendations. Michael and Bryan also discuss: Patience and caring about outcomes of jobs Water temperature and quality effects on system operation Environmental concerns Maximizing efficiency in geothermal systems Geothermal sales and economic trends Return configuration Sharing loops Figuring out gallons per minute and delta T Pump-and-dump configuration Clogged heat exchanger symptoms Identifying problem areas Loop temperature variations   Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan explains what water vapor diffusion is. He also explains why it matters to the everyday HVAC technician. Vapor diffusion is the transfer and distribution of water vapor through a solid surface. New constructions sometimes have vapor barriers on the outside of buildings in hot, humid climates or on the inside of buildings in cold, dry climates. (Even so, vapor barriers are not 100% effective.) We are NOT referring to water or mist wicking through the buildings via capillary action; we are referring to water vapor. Drywall, a common building material, is quite permeable and allows moist air to diffuse through it. The vapor diffuses through the drywall from the unconditioned attic to the conditioned living space. Of course, we have to focus on air sealing before anything else, but we also may need a vapor inhibitor or a means of controlling the attic dew point to prevent water vapor from moving through. The driver that causes moisture to move into the space is surprisingly NOT relative humidity. Instead, we need to focus on the actual moisture content as a driver, and it would help us more to look at the dew point. Dew point is the key to controlling vapor diffusion. If the dew point in the unconditioned space is higher than that of the conditioned space, then you will get vapor diffusion into the conditioned space. However, if the dew points are the same in the conditioned and unconditioned spaces, then there won't be a differential that would cause vapor to move.   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 live conversation, we discuss some real-life situations with difficult customers. We also cover some helpful tips we learned along the way. When Bryan started Kalos, there was one situation where a customer blamed him for lying about a customer diagnosis. So, that was how Bryan fired his first customer. However, many of us want to fire several customers, and that's when we have to look in the mirror and evaluate ourselves. When the problem truly isn't with us, we have to make a choice to say, "Sorry you feel that way," and walk away after we've tried our best. Sometimes, customers will demand that certain procedures are done or certain systems installed. Even if we were to give in to their demands, difficult customers would still be inclined to blame us, so it's up to us to assert our boundaries and do the job correctly. We also need to stop saying that our work is "easy." When we say that work is "easy," it appears to cheapen our work in the customer's eyes. We may encounter customers who are a bit neurotic or who want to take advantage of us. In those situations, the best thing we can do is take the customer seriously and take full responsibility for our work: carry out tests, answer questions, and solve the issue. The manufacturer may do very little to help a situation, so we must be prepared and knowledgeable. We also discuss: Bryan's Christmas pool heater meltdown Commercial HVAC/R finger-pointing Being "good with money" and how that translates to doing good business Valuing our work Working for family members and charging them A ductless disaster with a nervous customer "Calm down" Listening productively Setting expectations Pricing and making a profit Moving on from failing customer relationships Buyer's remorse   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, Henry Papa from Sporlan joins us in person to talk about refrigeration case controllers on systems with common compressors. We focus on the Sporlan S3C case controller, but some of the information applies to other case controllers. Case controllers control the conditions at each separate evaporator and are responsible for controlling defrost, discharge air temperature, and superheat. They can also monitor conditions at the evaporator, especially discharge air. In grocery, we tend to look at discharge air temperature instead of box temperature. Traditionally, we use EPRs to control a fixed evaporator pressure to control the discharge air temperature. With the S3C refrigeration case controllers, we can assess the discharge air temperature directly. The greatest advantage of the S3C controller is that it is NOT a single centralized control. Those standalone case controllers communicate with each other but work independently. So, if one rack goes down, the rest can keep running. On traditional controls, all of the racks could go down if one goes down. The S3C controller is also quite serviceable and connects to Bluetooth. So, you can sync the case controller display's data to your mobile device for convenient viewing. You can also control a few different functions from your device. However, you must take some time to understand the parameters, inputs, and outputs, as with any other controller. The goal is to read the manual and get comfortable with the details before working with the controllers. Henry and Bryan also discuss: Sporlan's podcast and training resources Parker-Sporlan relationship Demand defrost Alarm systems on refrigeration case controllers Dual-temp control Electronic EPRs vs. traditional EPRs Becoming "masters of the obvious"   Check out Sporlan's Chill Skills online training 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 short podcast episode, Bryan talks about brazing and soldering. He also weighs in on patching and if it is an allowable repair. Brazing is when you use a dissimilar metal to join metals at a temperature above 842°F, and soldering occurs at temperatures below that. (Welding occurs when you use the same metal as a joining metal.) In our trade, we generally use soldering on copper plumbing and brazing on line sets. We also often call brazing alloys "solders," such as silver solder. When making a joint, you want to have a sufficient (but not oversized) gap between the male and female surfaces of the joint. That's because the joint needs a large surface area where the solder or alloy can flow in via capillary action. Temperature is critical, as it needs to be high enough to draw the alloy into the joint, but it can't be too high. Patching is a controversial practice, but you CAN do it. If you are going to patch a system, it's best to do it on the low side of the system at a low temperature and with minimal vibration to minimize the risk of damage. Unlike traditional brazing, patching is when you use an alloy to seal up a small crack or leak; you don't want to draw the alloy into the joint. If you decide to patch, one of the best alloys you can use is 15% silver solder. You also risk blocking the tube. If you can cut the leaking section out and patch it with a coupling, that's an even better practice. We DON'T recommend patching on the discharge line at all.   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.

n this live podcast episode, we have a fun conversation talking with Nathan Orr and Kevin Compass about grocery refrigeration. The most common types of calls are those where the machine is "not making temp." Usually, the cases can't maintain temperature due to frozen evaporator coils or backed-up drains. On low-temperature/freezer applications, we must rely on electrical or hot gas defrost to mitigate frozen coils. Hot gas defrost is a complicated but quintessential part of low-temperature grocery refrigeration because the coils easily freeze. The discharge gas has to go to the evaporator coil and merge back into the liquid line; that gas CANNOT make its way to the suction line without causing damage, so the liquid line pressure needs to remain lower than the discharge line pressure. Kevin sometimes recommends running the fans all the time in open cases because the fans aid in the defrosting process, especially when it comes to warming the drain pan. Another common issue that refrigeration techs encounter is starved coils. Clogged TXV screens often cause starved coils, but we don't usually replace the entire TXV in grocery refrigeration. Instead, we only replace the part that needs replacing (the screen). The same practice applies to other TXV components; we replace only the powerhead if the powerhead has an issue. Most grocery refrigeration systems use refrigerants that are quite different from residential HVAC refrigerants. Some of the most common refrigerants are propane and carbon dioxide. However, propane is flammable, and CO2 doesn't work very well in hot climates. Nathan, Kevin, and Bryan also discuss: Electric vs. hot gas defrost Walk-in boxes Bunker cases/coffin cases Hoarfrost Water heaters Defrost termination Offsets and thermistors Underground line sets Charging refrigeration systems for a wide range of ambient conditions Ammonia refrigerant   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.

Nathan Rothenberg and Ed Janowiak join Bryan to talk about the good, the bad, and the uncomfortable of ACCA Manual J, D, and S. Manual J load calculations exist to make the BTU inputs and outputs predictable. Then, Manual S comes in to assist with equipment selection to meet the load calculations and the customer's comfort needs. Manual D is a collection of mathematical formulas that exist to help you calculate your friction rate, which is important for comfort in terms of noise in the ducts (from excessive air velocity). Ed believes that the best way to learn Manual J is from the physical manual; several instructors will teach the calculations straight out of the book, not on computer software. The difficulty of learning Manual J is one of the manual's shortcomings. Also, while Manual D is often required by code, Manual J is not often required, meaning that technicians can get away with poor designs. A common argument against Manual J is that comfort needs also tend to vary with each customer; therefore, standardized calculations and targets may not help individual customers meet their preferences. The typical temperature and humidity targets are 75°F at 50% relative humidity. Under those conditions, the dew point is 55°F (meeting the 20°F delta T rule of thumb), meaning that the air should remain well above the dew point. When the air remains above the dew point, the risk of a moisture problem greatly decreases, even at the expense of comfort. Nathan, Ed, and Bryan also discuss: Bad square-footage rules of thumb ACCA Manual T (register placement) Temperature and humidity effects on comfort Oversizing equipment Single-stage vs. two-stage equipment Ductwork in unconditioned spaces   Check out the ACCA website at acca.org. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

In this short podcast episode, Bryan compares under load vs. bench capacitor testing to find out which testing method is better. When we test the system while the motor is running, we call that testing under load. Testing under load is fairly easy; you take the voltage across the capacitor (V), amperage off the capacitor's start winding (A), and then you use the following math problem: (A x 2652) / V (You can also punch those numbers into the calculator on the HVAC School app.) While you can test under load on an off system, the test will provide a more accurate picture of the operating capacitance if you perform the test while the system is running. On a bench test, you disconnect the leads, discharge the capacitor, and test it with a capacitor tester. The tester will charge and discharge the capacitor; then, it will measure the amount of current going into and leaving the capacitor. The voltage will be lower than on a test under load. If either of those tests yields vastly different results, then it's likely that one of your readings is incorrect; it's unlikely that the performance differs that much under load or on the bench. For example, some ammeters can read higher or lower than the true amperage value, which affects the total capacitance in the math equation. Capacitors merely have foil plating and oil to make them work. The attraction between those forces creates a charge. Normally, these shouldn't "overheat." The plate-to-plate surface area can break down over time, leading to poor capacitance. Capacitor testing gives us a picture of the capacitance, and the state of the compressor materials could provide an explanation for the test results.   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.