Hvac School - For Techs, By Techs

In this short episode, Bryan goes over the fourth chapter of his new book, Unconformed. The chapter is called "So... What Do You Do?" Parents always want to be proud of their children, but it seems as though children are more proud of children who attend college than take up apprenticeships. However, these feelings largely seep in due to peer expectations; we want our children to measure up to our friends' standards or success, not necessarily our own. Parents are also less likely to encourage their children to get into the trades and value the time and expertise of tradespeople. All jobs, even less prestigious jobs, matter and have a purpose. Society tends to devalue tradespeople and manual laborers, but those jobs do a great service to society. Nevertheless, the competitive drive between parents and our fear of failure makes us fall into these mindsets where we devalue manual labor. The media and family members also trap us in these expectations. Society runs on the ability of people to solve problems and i

This podcast is based on a Kalos meeting about pipefitting best practices, particularly in commercial refrigeration applications. It begins with a few words about quality workmanship by the Kalos founder and CEO, Robert Orr. Pipefitting consists of repairs and joining metals; when joining metals, we need to liquify the alloy and draw it into the joint via capillary action. When pipefitting, oxygen can present some problems by coating the inside of the pipe with oxides that can contaminate the system. We can reduce the likelihood of oxide formation by flowing nitrogen while brazing; purging nitrogen displaces the oxygen in the lines before brazing, and flowing keeps oxygen out during the brazing process. Tip selection will be based on the piping diameter; tips that are too small won't adequately heat the pipe, and tips that are too large will consume too much fuel. You'll also need to leak-check your torch tanks and ensure that you have the appropriate ratio of oxygen to acetylene by aiming for a neutral flame

In this short episode, Bryan talks about filter driers and their important role in HVAC/R system protection, especially in accordance with Copeland's (formerly Emerson's) AE24-1105 R5. We can really start keeping our systems contaminant-free by handling tubing properly, purging and flowing nitrogen, and keeping copper shavings out of the tubing when deburring or reaming. Suction and liquid filter driers protect the system during operation and are designed for specific purposes. We typically don't install suction filter driers in residential systems unless we're fixing a system with compressor burnout or acid contamination; in those cases, we also want to make sure we replace accumulators and clean out the line set as well as we possibly can. Commercial refrigeration tends to have more rigorous contamination prevention protocols, including testing oil for acid and installing suction filter driers in everyday operation, due to the use of multiple compressors in a single system.  However, suction driers are reco

This podcast episode is one of Alex Meaney's HVACR Training Symposium presentations: HVAC Design Backwards, Forwards, and In Between. Load calculation factors in all three means of heat transfer: conduction, convection, and radiation. It doesn't directly tell you the tonnage; it just tells you how many BTUs (sensible and latent) are entering or leaving a structure. When designing systems after doing load calculations, we need to be mindful of industry standards and their pitfalls, as well as the climate conditions and the difficulty of obtaining manufacturer data. Equipment selection by tonnage is only part of the picture when it comes to HVAC design; we also need to factor in airflow and duct design, especially duct sizing. However, many rules of thumb and poorly explained terms are counterproductive to a thorough understanding of HVAC design. In some cases, the best way to design a system may seem "backward," especially when starting with blower selection instead of ductwork. Duct design is particularly dif

This podcast is the Santa Fe Panel from the 4th Annual HVACR Training Symposium. The panel focused on dehumidification, was moderated by Nikki Krueger, and featured Andy Ask and Ken Gehring. "Matchmaking" a residence to the climate requires us to design and install equipment that keeps occupants healthy and comfortable. HVAC contractors need to focus on the dew points, especially as they remain high at night and in the shoulder seasons. Humidity loads tend to hold steady (even peak dew points), while sensible loads increase and drop, making it difficult to control latent heat loads the same way we control sensible loads. The equipment will typically be less efficient if you focus on long runtimes to remove latent heat under partial load conditions and maintain 50% humidity. Dehumidifier efficiency is determined on a pint per kilowatt basis, but a constantly running dehumidifier will do its job a lot more efficiently than one that starts and stops regularly. The dehumidifier adds heat to the house and should o

In this short podcast, Bryan talks about where to place the micron gauge during evacuation and how to think about micron gauge positioning. Evacuation (deep vacuum) doesn't remove solid contaminants, and vaporizing liquid water is a time-consuming process; its main purpose is to remove water vapor, air, and nitrogen gases from the HVAC/R system. When you pull down below 500 microns and hold that pressure, we can make sure we have a clean, dry, and tight (leak-free) system. As we started using R-410A and POE oil, water in the system became a much bigger issue than it was with mineral oil (it was never to have water in the system, but it breaks down POE oil). Before we start pulling a vacuum on the system, we need to attach our micron gauge to the pump while it's isolated to make sure the pump is working. A modern vacuum pump should pull down below 100 microns in 30-60 seconds; if your pump can't pull down to 100 microns in under a minute when isolated, then you'll want to change the oil (possibly multiple time

Brett Wetzel joins the podcast to talk about his journey from resi tech to industry-leading refrigeration trainer. Brett is best known for his educational content, but he is also the manager of technical troubleshooting and training at CoolSys. The skills gap is widening, and CoolSys was inspired to create a solution to that problem. Brett's goal is to offer training that provides education and a sense of community all at once. Since he likes to keep his training simple and establish a solid foundation for his students, one of Brett's favorite training practices includes going over a system's P&ID diagram with his students before even looking at it. He focuses on classroom engagement and keeping trainees interested. Brett does regional training sessions and has written technical documentation to help technicians. As he has shifted from a field role to a full-time educator role, he has noticed that he has had more time at home. CoolSys focuses on commercial and industrial refrigeration, including system co

In this short podcast episode, Bryan gets into some oil talk, covering some common refrigerant oil terms and types. Esterification is the process by which organic acid and alcohol come together to form polyolester (POE) oil and water. Hydrolysis refers to the decomposition of a substance when it comes into contact with water; when POE mixes with water, it will break down into esters, organic acids, and alcohol. Once POE oil undergoes hydrolysis, the process can't be reversed to get the same original oil. POE oil is also hygroscopic; hygroscopicity refers to the ability of the oil to absorb moisture. Miscibility refers to the ability of an oil to mix with refrigerant and be carried with it. In the context of refrigerant oil, "polar" refers to a molecular structure with an uneven distribution of electrons; oils with polar structures attract water molecules. Solubility refers to how well one compound can dissolve into another. Mineral oil is a product of the distillation of crude oil and was common in systems th

In this short podcast episode, Bryan talks about using a megohmmeter on a scroll compressor (or "megging" a scroll). Scroll compressors are among the most common compressor types nowadays, and they come with their unique needs and best practices. You can't pump them down into vacuums (in many cases, you can't do that anyway due to internal protections), run them in a vacuum, or run a high-voltage megohmmeter or hipot test. Scroll compressors differ from reciprocating compressors. A scroll compressor's motor is located at the bottom of the compressor, meaning it is immersed in refrigerant and oil when the system is operating AND when it is off; when the compressor is off and cold, there is a chance that there will be liquid refrigerant at the bottom. Compared to reciprocating compressors, scrolls tend to have a more compact and balanced design, and there could be a higher risk of internal arcing due to the tighter electrical tolerances associated with the design. Many inexpensive megohmmeters will say that any

Matt Bruner joins the podcast to talk about what it's really like being an HVAC creative. Matt is a young HVAC business owner who has recently written several HVAC School tech tips and pursued creative interests in the trade. Being creative in any industry or aspect of life requires us to be aware of what's around us and think deeply about how things can be better. Creativity requires us to channel our dissatisfaction into finding a solution, not just complaining, similar to how children channel boredom into projects. While the industry relies on processes and procedures to establish consistent standards, an over-reliance on processes can remove opportunities for HVAC professionals to be creative in their careers. However, creative solutions still need to be based on a solid understanding of the scientific and safety fundamentals of the trade. In many cases, processes get better when people are allowed to be creative and tweak existing models and ways of doing. There is plenty of room for creativity in the de

In this short podcast episode, Bryan talks about TXVs and their impacts on energy efficiency ratings (EER and SEER). EER (Energy Efficiency Ratio) is calculated based on fixed conditions (an outdoor temperature of 95 degrees Fahrenheit and an inside temperature of 80 degrees with 50% RH). EER is a ratio of cooling-only capacity in BTUs per hour to the total electrical input in watts. SEER (Seasonal Energy Efficiency Ratio) is the ratio of an HVAC system's cooling output during a typical cooling season to the seasonal electrical input in watts. Both energy efficiency ratios use non-proportional units (BTUs to watts), but SEER is supposed to account for a wide set of conditions (even though the climates of regional markets can vary quite wildly). EER2 and SEER2 are new standards based on updated equipment testing protocols with more realistic static pressures. TXVs and EEVs can modulate to control the amount of refrigerant going into the evaporator coil. TXVs maintain a set superheat at the evaporator coil outl

Jim Ball from NCI joins the podcast to talk about high-performance maintenance contracts and agreements. A high-performance maintenance agreement requires you to take system measurements and present solutions to maximize performance accordingly and exceed customers' expectations, not just make assumptions about the performance parameters. Key measurements we should know include the charge levels, total external static pressure, filter & coil pressure drop, and CFM per ton. Many HVAC contractors and technicians don't really believe in maintenance procedures; some contractors merely want to keep customers or secure work during the shoulder months and don't aim to optimize the homeowners' systems. Maintenance procedures provide technicians and contractors the opportunity to improve the health and comfort of their customers. To perform a quality maintenance procedure, we need to establish company-wide processes that produce consistent results. When we standardize maintenance and installation procedures, we wa

This episode of the HVAC School podcast Steve Coscia's symposium presentation: HVAC Soft Skill Training Resources. Likability is a superpower in any job that requires you to interface with customers or students. Every word and mannerism your customer or student sees will matter, and it's important to be likable. Those impressions can heavily influence their decision-making. Making a good first impression is one of the most important areas where we can focus our soft skills, and being on time is an easy way to make a good first impression on customers. When we are pleasant and convey mastery of our craft, we become more likely to earn appreciation and respect from customers and fellow tradespeople. Delegating the authority of the class is a soft skill that is important for instructors, as it encourages participation and lets a student be recognized by their peers. Telling a "signature" story, using props, and making the classroom interactive also help you convey useful information to your students and keep the

Roman Baugh returns to the podcast to talk about the time he installed an A2L system and lived to tell the tale. Roman used most of his same R-410A tools to install the first A2L-based ductless mini-split in Florida. Flare blocks, wrenches, and torque wrenches will all stay the same; you just have to be sure that your vacuum pumps and recovery machines are rated for use on A2L refrigerants. A2L-based mini-splits use flared fittings with no brazing necessary; this is currently the A1 status quo.  Purging and flowing with nitrogen will be required of A2L systems. Purging refers to a higher flow rate and flowing refers to a very low flow rate (2-5 standard cubic feet per hour). If a pipe may have refrigerant inside of it, we will need to cut the pipe with a copper cutter, not use a torch. You will need to store A2L refrigerant tanks upright and locked in your van. You'll want the tanks to avoid being banged around or struck by other objects in the van. Although A2Ls are non-toxic, they still displace oxygen if a

In this short podcast episode, Bryan talks about motor speed and other basic electrical topics as they relate to motors in HVAC equipment. In a typical single-phase PSC-type (induction-driven) motor, the speed is primarily determined by the electrical cycle rate, also known as the hertz. The hertz represents the speed at which the electrical current changes direction (positive to negative) per second; in the USA, that number is typically 60 hertz. Unless we're dealing with ECMs and VFD-driven motors, the motor speed will be partially influenced by the hertz or frequency as determined by the utility company or a generator. Motor speed is also determined by the number of magnetic poles in the motor. A motor doesn't make a complete revolution per cycle; a cycle only refers to the distance between two poles. The more poles we have, the shorter the distance needs to turn per cycle. A two-pole motor rotates all the way every cycle, resulting in 3600 RPM under no-slip conditions (synchronous speed). A four-pole moto

Trevor Matthews returns to the podcast to talk about growing in productivity and confidence as a tech to avoid feeling stuck in your career. They talk about personal development within your organization and in communities or training courses beyond your organization. Confidence and productivity work hand in hand, and techs can grow in both areas when they prioritize the one that matters most to them. In many cases, repetition helps build confidence, especially in the trades and other professions where you work with your hands. Scheduling is another strategy that improves your productivity, which can boost your confidence in the long run. As humans, we tend to fixate on fears and problems. We can build our confidence by reframing our fears, giving ourselves (and others) grace when we make errors, and focusing on building our skills to work through challenges. It's also important to find people in your organization who will uplift you, not hold you back. Developing unhealthy habits is a possible consequence of

This podcast episode is Alex Meaney's 2023 HVACR Training Symposium session: "The Art of Unteaching." We may have flawed understandings of HVAC concepts, including the understanding that "heat rises." Our world is constantly shaped by the things we see and believe, and we are hard-wired to defend our observations and beliefs if we feel that those are threatened by new information. Instructors need to be sneaky about "unteaching" flawed ways of understanding the scientific principles of HVAC. When we communicate concepts to others, we need to watch our language and make sure our messages are clear; the subtext is as important, if not more important, than the actual material. Humility also goes a long way when teaching, though teachers need to be especially careful of imposter syndrome.  Teachers can be most effective when they find a point of common ground between what their students already know and what they want to teach their students; avoiding jargon is a good way to make sure everyone can start on the sa

In this short podcast episode, Bryan talks about compression ratio and efficiency, particularly how floating or fixed suction and head pressure affect those things. Compression ratio (absolute head pressure divided by absolute suction pressure) closely correlates to efficiency in all sorts of compression-refrigeration HVAC/R systems; the most efficient systems have high mass flow with less compressor work. High compression ratios indicate a greater differential between the head and suction pressures. A lower compression ratio is desirable, but the number has to be realistic; a compression ratio of 1 indicates that the system is off. Medium-temp refrigeration compression ratios are typically around 3:1, whereas low-temp refrigeration can have higher compression ratios (6:1). In commercial refrigeration applications, we can help control the compression ratio with floating suction and head strategies. Floating the suction and head pressures allow the equipment to achieve lower compression ratios and higher equip

This podcast episode is Nikki Krueger (Santa Fe Dehumidifiers) and Bryan's 2023 HVACR Training Symposium session about how we can optimize dehumidification and efficiency to create an HVAC design and humidity utopia. While we attempt to achieve comfort and high indoor air quality in humid climates, we may find challenges integrating these with the HVAC system and getting customers to understand the need for proper dehumidification. Older homes that are built "leaky" allow for uncontrolled infiltration and exfiltration, but newer constructions are a lot tighter and rely on mechanical ventilation to control where the outdoor air comes from and make sure it is properly filtered and distributed. We deal with both sensible and latent BTUs in a home, and we can't treat them as though they're all equal. Many high-efficiency systems have high sensible heat ratios (SHRs) and are designed to remove sensible BTUs very efficiently, but they're not adequate at removing latent BTUs. Ideally, we would rely on an A/C system

This is the episode for you if you've ever asked, "What the flux?" In this short podcast, Bryan explains the basics of flux in soldering and brazing, as well as magnetism. Flux means "flow." In HVAC, "flux" may have two meanings. It may refer to the substance that helps the molten alloy flow and bond to base metals more effectively when you're soldering or brazing. However, flux may also refer to magnetic flux, which is the lines of force that emanate from a magnet; this concept is important in inductive loads like transformers. In soldering, brazing, and welding, flux is a powder-paste or liquid that you apply to the base metal. You usually apply it directly to the male side of the base metal, or it may be embedded in the brazing alloy. Flux prevents oxides (like rust or the black flakes, cupric oxide) from forming on the surface you're brazing, which commonly happens at higher temperatures. Flux helps you create a proper bond, but it doesn't eliminate the need to clean the base metal before brazing. You typ