HVAC School - For Techs, By Techs

Central Florida techs know the Southern winter all too well. Let's face it. It doesn't get super cold here regularly, but when it does, EVERYONE FREAKS. We get an abundance of service calls for unpleasant but not truly problematic conditions when people use their heaters. When people first turn on their heat, they can get a nasty surprise: a horrible dirty-sock smell and sometimes a shrieking smoke alarm. These are normal, albeit unpleasant, and do not require a service call. Another unpleasant or alarming occurrence is when a heat pump unit goes into defrost mode. Defrost mode shifts the unit into cooling mode, which may make some cold air come out of the vents. On top of that, customers may hear an awful noise and feel concerned when they see steam coming out of their unit! Pool heaters are a completely different animal in a Southern Winter, and they are often made quite poorly. You may come across gas pool heaters, propane pool heaters, heat pump pool heaters, and even solar ones. Each type has its own set of maintenance needs and varying degrees of effectiveness. When working with them, the goal is to set establish realistic expectations and explain best practices to the customer to minimize those frustrating service calls. In this episode, we talk about: Burning off heat strips Heat pump defrost mode Gas pool heater Heat pump pool heaters The thermodynamic principles of heat pump heating Defining BTUs Liquid petroleum (propane) vs. natural gas And much more... This podcast is in an unedited "meeting format" and is not usually the type of thing you will get on HVAC school, but I still think it may benefit junior techs and office staff. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode of the HVAC School Podcast, Bryan talks with Jeremy Smith about refrigeration tips, terms and processes. They also cover the similarities and differences between A/C and refrigeration. Being on-call as an A/C tech is not all that different from being on-call as a refrigeration tech. Similarly, the principles of heat transfer don't change between the A/C and refrigeration trades. Both trades follow the same basic rules, but all of those valves, adjustments, and tuning on rack refrigeration systems may make an A/C tech's head spin. Refrigeration techs may come across glycol chillers, rack refrigerators with several refrigerant circuits on a single piece of equipment, or piping that has been warped by hot gas defrost. There is also a greater emphasis on regulating suction pressure rather than merely measuring it, and refrigeration techs use EPR valves to help control that pressure. Each refrigerated case also has its own expansion valve. Jeremy also covers the complexity of defrost. In A/C, defrost could be as simple as shutting a unit off for a period of time. Defrost is more critical in low-temperature applications, though hot gas defrost may damage pipes and make them prone to leaks. Electric defrost typically has a lower potential to cause damage. Also, subcooling is less of a big deal in refrigeration. Sight glasses and receivers make subcooling less vital than it is in HVAC. Join Bryan and Jeremy as they discuss: Reznor startup Being on call in the refrigeration world Differences and similarities between rack refrigeration and A/C Hot gas and electric defrost Glycol refrigeration systems Subcool and superheat Refrigeration TXV settings EPR valves and their settings Rack manifold pressure   And many more refrigeration tips... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode of the HVAC School Podcast, Bryan talks with Tim Bagnall about flowing nitrogen. Many techs don't flow nitrogen. Some may say that it is overkill, but it has been shown that flowing nitrogen displaces oxygen while brazing and prevents harmful scale from forming on the copper. Scale is very problematic, and it will likely ruin your copper lines if you keep those lines open to air. (The jury is still out as to whether climate/geography affect scale formation, though.) There are many different intensities for flowing nitrogen, particularly high-pressure purging and low-pressure flowing (2-5 SCFM). You may also have heard that you should flow nitrogen at 1.5-3 PSI, though SCFM is the preferred unit. Some best practices for flowing nitrogen while brazing include using wet towels or heat-resistant putty on the service ports, removing the Schrader cores, removing the TXV sensing bulb before brazing, and watching your torch control so that you do not overheat the metal. Join us today as we discuss the following: The proper tools and flow settings for brazing How the pressures should be set to SCFM and not PSI The possibility that geography may contribute to scale How to flow nitrogen in a practical way And much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode, Bryan goes back over the basics and stresses the importance of diagnosing the whole system. I'll cut to the chase: inspection is NOT overrated. Inspections help you become more familiar with HVAC systems and can help you catch on to minor issues before they spiral out of control. Check air filters, check the charge, check the evaporator coil... does the inspection checklist ever end? Whether you see crunchy brown contactors or oil on the lines, none of those issues are too small to warrant investigation and repair. Those may not seem worth the hassle, but a leak or low charge can negatively impact the A/C function over time, leaving you with unhappy customers. Checking everything may seem a little over-the-top, but it really is in your customers' best interest. The same goes for mundane procedures like cleaning out drains. We also have our controversial practice of the day: you don't NEED to remove a slant coil for cleaning all the time. Cleaning it in place is A-okay. Some of the system procedures I'll discuss include: Checking the charge completely Superheat and subcool Checking the evaporator coil Inspecting the filter Looking for wire rubouts Checking the drain line and drain pan Checking capacitors and contactors And much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this podcast episode, Bryan goes over best practices for diagnosing and replacing an A/C or refrigeration compressor.  When testing for a shorted compressor, make sure the compressor is isolated from all of its circuitry. You would see low ohms to ground in a shorted compressor. Do NOT measure from winding to winding or terminal to terminal to diagnose a short. You may also come across an open winding failure. In the case of an open compressor, the power is going to the compressor, but it’s not doing anything.  Locked compressors also go out on internal overload and draw high amps. Try your best to unlock the compressor but be realistic about the state of compressor health. Poor compression also indicates a failure. You would typically see low head pressure and high suction pressure with low system capacity. When replacing the compressor, you’ll want to start off by knowing the type of failure that was diagnosed. Reconfirm the diagnosis. Then, do your acid test and make sure you have a matching capacitor and enough refrigerant to do the job. Know your connection types, compressor model, and warranty status. Fully recover the old refrigerant charge and remove all existing driers in the system. Braze in the new compressor and pressurize the lines with nitrogen. Bubble-test all new joints and check them thoroughly. Then, pull your vacuum before adding charge by weighing a factory charge into the liquid line. When you power on the unit, monitor the performance and inspect the unit closely. Bryan also discusses: Clarification on flowing nitrogen Learning theory vs. application Pulling terminals off Proper megohmmeter use “Redneck” test (running the system without the compressor) Acid and oil testing Hard start kits and oil migration Accumulators and acid protocols Suction line driers Mufflers Vacuum pump oil   If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.  

In this episode of HVAC School, Bryan covers the "5 pillars of refrigerant circuit diagnosis" and why they matter. They are: Superheat Subcool Suction pressure Head pressure Air temp split (delta T) These 5 readings give you a holistic idea of the A/C system. Instead of getting hooked on checking only superheat and subcool all the time and dismissing potential diagnoses, you can use these five readings to get an idea of the health of several parts of the system. Making it a priority to take these five readings also promotes open-mindedness, which is perhaps one of the most vital qualities of a diagnostician. The five pillars will give you the clues to diagnose overcharge or undercharge, a wide variety of restrictions, kinked suction lines, expansion valves failing open, improperly seated pistons, condenser fan issues, and so many more conditions. Also, regularly check and calibrate your tools. These 5 readings won't be helpful if you aren't constantly making sure your tools are accurate. As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

In this episode of HVAC School, Bryan talks to his sons about basic electrical theory. Electrical theory normally requires trigonometry, calculus, and all of those fun maths. However, the basics are so easy that a 12 and 14-year old can figure it out. Electrical theory follows many of the same principles as thermodynamics—however, electrical theory concerns charges rather than heat. Conductors and insulators behave similarly with electrical charges as they do with heat. Ohm's and Watt's laws establish what volts, amps, power, and resistance, and they explain the relationships between those units. However, magnetism can add a bit of confusion to those equations. We drive motors with inductive loads, making Ohm's law seem invalid, but the magnetism resists itself, which goes unnoticed on ohmmeters. That is untrue of DC motors, and Ohm's and Watt's laws will appear to check out under most circumstances. An electrical component can fall into three main functional categories: power source, switch, or load. If something doesn't fall into one of those categories, it merely adds resistance. The power source could be a transformer, which provides homes with power from the power company (and goes from a higher voltage to a lower one that our appliances can use). A switch opens/closes or rewires an electrical path, and a load is what does the work. That's the short of it, but it's still pretty easy. Join Bryan and his sons as they talk about: Differential charges Electromotive force Ohm's law Volts, Ohms, Amps, and Watts Electrical paths Conductors and insulators Resistive and inductive loads And much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.

This episode of HVAC School is a Kalos meeting where Bryan talks to his team about an incident where a leak was erroneously detected on the evaporator coil. The system was three months old, and one of our junior techs diagnosed a leak on the evaporator coil. (What?? That never happens!) So, the customer was quoted for a new evaporator coil. One week later, the charge was low again. The junior technician quoted the customer for more refrigerant charge and leak detection. The customer freaked out. Unfortunately, there were so many things we could have done to prevent the hassle and frustration for the customer. All was fine in the end, but we could have gathered more data to perform a more thorough diagnosis, sent out senior technicians to verify the issue, and kept the bigger picture of the service call in mind from the start. During this meeting, Bryan stresses the importance of: Reconfirming parts before installing them Performing a complete diagnosis Using a micron gauge Becoming a valuable technician And much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this episode of HVAC School, we discuss the entire basic refrigerant/compression refrigeration circuit. We are in the business of moving heat. Heat refers to motion in the molecules. Temperature is the average velocity of those molecules. Heat needs a temperature differential to move. So, HVAC systems absorb heat when the refrigerant is colder than the ambient temperature. They reject heat when the refrigerant is hotter than the ambient temperature. Remember the components and their functions in the following order: Compressor: increases the vapor refrigerant's temperature and pressure. Discharge line: carries hot, high-pressure, superheated vapor to the condenser. Condenser: changes the vapor to a liquid. Liquid line: moves the subcooled (high-pressure) liquid to the metering device. Metering device: drops the liquid's pressure (creates some flash gas). Expansion line: leads the low-pressure liquid/vapor mixture to the evaporator. Evaporator: changes the liquid/vapor mix to a vapor. Suction line: moves superheated vapor to the compressor.   Note: Heat pumps can shake things up a bit; the suction line becomes the discharge line (and vice versa), and the condenser becomes the evaporator (and vice versa). However, heat pumps have two metering devices and a bi-flow liquid line drier, so the liquid line stays the same. So, watch out for heat pump systems with that tricky little reversing valve. We also elaborate on some fancy accessories. These include accumulators, discharge line mufflers, receivers, and more. And we discuss much more... As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE.

In this episode of HVAC School, I talk with my brother Nathan... and he whines a lot about cool tools I like. As you might have guessed, Nathan is in the camp of people who believe that proper training promotes good practices; fancy tools won't make an outstanding tech. Even though I respectfully disagree with him on some things, he has a point. Tools will only be useful if a tech knows how to use them. They should make your life easier, but they shouldn't have much bearing on performance. He doesn't like wasting money or time on tools that probably won't help him. So, he doesn't like solder rings or thermal imaging cameras. On the other hand, I'm in the "tool nerd" camp. I love new technology and think tools can make us do much better work if we learn how to use them properly. On the job and in my spare time, I enjoy reading up on the latest technology and trying out the newest tools. Missing out on the newest "wow!" tools is a fear of mine. Spending money on a tool that will help me do better, more efficient work is ALWAYS worth it. I think solder rings and thermal imaging cameras are cool and can be put to good use. We talk about how efficiency, organization, training, job performance, and customer trust relate to tools. We can find some common ground in some areas, even if we have fundamentally different attitudes toward tools. Oh, and we talk about digital gauges and the jumping spider that lives in Nathan's van. —Bryan As always, if you have an iPhone, subscribe HERE, and if you have an Android phone, subscribe HERE. Check out our handy calculators HERE.