Hvac School - For Techs, By Techs

Nikki Krueger and Genry Garcia return to the podcast to talk about a recent IAQ & dehumidification case study on a vintage home in Miami. The home was very clean but had a musty odor and VOC concerns. You can read the case study in the “Literature” section at https://www.santa-fe-products.com/about-us/media-resources/ or https://hvacrschool.com/case-study.  Blower door tests and ZPD revealed that the home was leaky, and the crawlspace was also not properly encapsulated. The options were to tighten the building and/or mitigate the problem by improving the HVAC system. The homeowners chose to improve the HVAC, which Genry did by installing a ventilating dehumidifier (Santa Fe Ultra98H), reducing system tonnage (3.5 to 2 tons), and putting in new ductwork. One of Genry’s key tips to address intermittent moisture issues is to pay attention to fluctuating pressures, not just under the blower door test conditions. Ongoing monitoring is crucial in these studies to measure the home under several different typical

Skilled trades entrepreneur Tommy Mello joins the podcast to talk about creating a business where everyone wins: business owners, employees, vendors, AND customers. Tommy's main motivations in business are relationship-building and helping employees make a good living. Those motivations contribute to the development of company culture; even though cultures build themselves naturally, developing the right leaders will help build a positive company culture that values all employees equally. Tommy trains leaders to develop their strengths, shows them that they are valued, and gives them the resources they need to succeed. When companies grow, communication tools and project management technologies need to be standardized to help organize the company, including using checklists and SOPs. Departments also need to keep their focus on the company's main goal, not just the success of their division. The goal is to make sure that people are aware of their responsibilities early on and on board with the company's visio

Refrigeration Mentor Trevor Matthews returns to the podcast to share some of his tips for supermarket rack service. The supermarket refrigeration world is ripe with high-paying opportunities and uses similar skills that HVAC technicians use daily. Switching from HVAC to refrigeration will require a little bit more attention to some new components, especially controls and control systems. Technically-minded people tend to do well in the refrigeration field regardless of where they come from. When you're sent to a job site, you'll need to investigate the store and the case (where the refrigeration happens) before checking the controller and looking at the alarms and trends. As with HVAC, you'll want to start by looking for the obvious, like frozen drains. (Even though these systems are designed to freeze, we still need proper airflow and don't want standing water in the drains to freeze.) We don't want to go in there with our tools and start adjusting valves immediately. Attention to detail is critical in refri

In this short episode, Bryan covers traps, vents, and drains. He explains some common misconceptions and best practices for fabricating drains, especially in residential and light commercial structures in Florida. Cleanouts and vents are commonly confused with each other, and people often cap vents and leave cleanouts open. However, cleanouts (which must be capped) will always be before the trap, and vents come after the trap. When you have an indoor air handler, furnace, or fan coil, vents must be higher than the drain pan to allow the float switch to trip when the drain backs up. (Rooftop units have shorter vents.) Vents should stay open. We use static pressure to determine the trap depth, and the trap outlet must be shorter than the inlet. The best practice for drain pitch is to have 1/4" of fall for every foot of horizontal run, and we must avoid making double traps where air can get trapped between them. Vents prevent air bubbles from forming in drains with multiple traps. Double traps often form when dr

HAVEN IAQ founder and CEO Kevin Hart returns to the podcast to discuss cracking the home health comfort code, diving into IAQ’s illusory ideals. Even though the industry has been generating well-thought solutions to common problems, it’s difficult to put those solutions into practice on a large scale. As a result, it’s common to rely on selling “bolt-on” IAQ products, which don’t actually solve systemic IAQ problems. HAVEN’s recent work has also shown that only a few HVAC technicians are proactively offering IAQ solutions to homeowners; the vast majority wait for the owner to ask about a solution instead.  Some IAQ issues stem from duct and building envelope leakage, meaning technicians could offer to perform diagnostic tests (like blower door testing) and address the solution holistically with building envelope and duct sealing. However, not all customers are willing to pay for these, which is one of the biggest challenges of comfort consultations. The question about the real long-term, widespread effectiven

In this short podcast episode, Bryan goes over a few tubing insulation tips. Tubing insulation is also commonly known as Aeroflex, Armaflex, and Thermaflex—all brand names for black copper line set insulation. We typically have to insulate just the suction line in typical residential split HVAC systems, but you'll typically have to insulate both lines in ductless/VRV/VRF or refrigeration applications. The insulation should be on the tubing before brazing, gluing the ends together (only using a specialty tubing insulation adhesive, NOT duct tape!). Since these adhesives are types of contact cement, you will need to apply a thin coating on each side of the joint and wait for a few minutes before pushing the ends together. Some forms of tubing insulation are split and have an adhesive flap instead. Then, you'll want to hold the insulation back with a clamp about 8-10" away from the area where you're brazing to protect it from heat damage. When you finish brazing, you'll want to put the insulation back and make s

Jim Fultz returns to the podcast to talk about the new HSI module from White-Rodgers, the 50E47U-843. You can learn more about this new universal HSI module at https://hvacrschool.com/hsimodule.  Hot surface ignition modules control the burner for gas appliances that use hot surface ignition, not just furnaces. Since the HSI module doesn't need to work with a blower fan, it can be used in water heaters, pool heaters, and many more appliances that don't primarily move air (except for combustion). It also controls the inducer blower and monitors the pressure switch. All White-Rodgers universal ignition modules work with the WR Connect app, which allows users to set up controls with a smartphone via NFC technology. The controls do not need to be powered on, and users do not need to be online during use. Users can also use the app to auto-configure their new White-Rodgers controls based on the old control settings. Technicians aren't required to use the app and can configure controls manually if desired. Universa

In this short podcast episode, Bryan talks about locked compressors and hard starts. He explains what actually happens when a compressor locks and covers when and how to use hard starts appropriately.  Locked compressors are compressors that trip on overload during startup; they're considered "locked" because the rotor doesn't turn inside the stator and generates heat instead. The overload opens, but the compressor shell typically does not heat up very much when the overload opens.  When you have a locked compressor, you need to start investigating the root cause with a thorough visual inspection. Then, check the run capacitor. A hard start kit helps you get the equipment working, but we should make sure we've addressed underlying electrical issues or installation conditions before installing a hard start kit. If the unit is old, then we may use a hard start as a temporary solution until the customer can purchase a new unit. In any case, it's best to use a factory hard start if the system requires it, but it'

Licensed mechanical engineer Tony Amadio joins the podcast to talk about residential exhaust codes and best practices. He also put together a presentation about the topic, which you can view at https://hvacrschool.com/exhaust.  When choosing duct materials for residential exhaust, you will want to stick to sheet metal and mind the gauge; flex ductwork can easily be damaged and will rack up a high total equivalent length in a way that sheet metal will not. Exhaust air should always discharge outdoors, not into an attic or crawl space, and that air needs to be replaced by air entering the conditioned space; makeup air is the air we draw in to replace the exhausted air, and we need appropriate undercuts to make sure we're getting the right amount of makeup air. Domestic cooking exhaust may also come in a few different varieties, each of which has different code requirements (with downdrafts needing much more CFM per ASHRAE). Range hood shape is also important for capturing as many particles as possible, but make

Phil Barr and Nathan Orr join the podcast to talk about wiring refrigerated cases in commercial spaces, including convenience stores and supermarkets. Cases may be medium-temp (or high-temp, in some cases) or low-temp. Medium-temp cases can typically defrost on their own during the off cycle, and low-temp cases may have electric or hot-gas defrost to help get ice off the coil at set intervals. Each system has an evaporator (and fans), compressor, condenser, and metering device (often a TXV or EEV), and low-temp refrigeration may have anti-sweat heaters, EPRs, and other components to manage. Challenges arise when electricians don't understand the fundamentals of commercial refrigeration, especially as the electrical circuitry relates to the refrigeration circuit components. Time crunches also apply a lot of pressure to electricians and refrigeration technicians. Testing circuits, such as fans and lighting, or using circuit tracers are good ways to get an idea of how an existing system is wired. Labeling wires

This podcast is a class taught by Bryan: Things to Keep Out of the System. He covers some installation best practices along the way to keep contaminants and non-condensable gases out of the system. We want to keep air, water, dirt, copper shavings, solvents, and nitrogen out of an operating system. All we want in an operating system is the appropriate oil and refrigerant for the system. Unfortunately, the POE and PVE oil we mostly use in residential systems nowadays are very hygroscopic; they attract water, and POE mixes with water to form acid, another thing we want to keep out of the system. We can pull most of the moisture out of the system by pulling a deep vacuum and following the best practices for a fast and deep evacuation. However, we can also reduce the probability of moisture getting into the system in the first place by NOT working on copper while it's raining outside, sealing the copper tubing adequately when routing it underground or in a chase (a common installation practice in Florida), and in

In this short podcast, Bryan talks about air changes per hour, also known as ACH, and what it means in HVAC design and indoor air quality (IAQ) discussions. ACH tells us how frequently the entire volume of air in a room or structure is replaced; we are referring to the cubic feet of air leaving a space and then being replaced within that same space. If we have a balanced number of cubic feet per minute (CFM) of air supplied to and returned from the room in one hour, we would multiply that CFM by 60 to get the ACH, as there are 60 minutes in one hour. ACH should not be used to calculate heat loss and heat gain, even though BTUs are moved with air. ACH is a practical guideline for HVAC design. Ventilation needs will vary based on the purpose of a room and the number of occupants in it, and ACH tends to be a more important factor for determining how we can meet ventilation needs in commercial and industrial structures than in residential structures, in which we mostly rely on Manual J calculations of sensible an

Roman Baugh joins the podcast to talk about oil return and the refrigerant charge in VRV systems. VRV systems—also known as variable refrigerant volume (or variable refrigerant flow/VRF) systems—have one outdoor unit, one or multiple compressors, and multiple indoor units. The outdoor unit modulates to meet the indoor units’ fluctuating demands. They are versatile and flexible systems. Like parallel racks, VRV systems have long lines and a lot of piping, so oil return and refrigerant charge are especially critical. VRVs have specific control protocols, as they need refrigerant volume and velocity to move oil and keep it lubricating the compressor for its entire lifespan; oil return mode, the refrigerant charge, and the piping protocols are supposed to support that function.  When it comes to piping protocols, line sizing is critical. Whenever there is a need to relocate the outdoor unit and change the piping configuration, the charge needs to be adjusted, and the piping may even need to be upsized to prevent

In this short podcast, Bryan talks about oxidation and all the buzz behind “magical air-cleaning oxides” and other similar IAQ products. Oxidation is the loss of electrons, and reduction is the gain of electrons; oxygen commonly loses electrons. Rusting is a common example of oxidation; it happens when iron and oxygen interact in air or water. Metals that are more likely to react with oxygen (or corrode) are “less noble” than more noble metals. Less-noble metals, known as anodes, are sometimes used sacrificially to prevent the oxidation of nobler base metals, known as cathodes. While iron oxidation results in corrosion, some IAQ products use the process to bind oxygen molecules to unwanted substances. The IAQ products that use oxidation use the natural tendency of oxygen to lose electrons when bonding with other molecules. Ozone is a common agent of these IAQ products because an ozone molecule is very unstable and has three oxygen atoms, meaning it combines with other molecules via oxidation; it stabilizes ot

In this short podcast, Bryan talks about filtration and IAQ, especially as they relate to virus control. He also answers the age-old question: “Can filters capture viruses?” While it may seem like particle size matters when it comes to filter efficacy, filters are not nets that strain air particles and prevent pollutants from passing through. When we talk about particles, we tend to focus on ones that are 0.3 microns in diameter, which tend to be medium-sized particles. Viruses tend to be among the smallest particles that we aim to control when it comes to IAQ. Filter media are crisscrossed fibers that catch particles in different ways. Inertial impaction is one means of stopping particles from passing through; the initial impact stops the particles from passing through. Interception happens when particles graze filter fibers and get stuck. Electrostatic attraction relies on energy to attract and catch particles. Diffusion happens when smaller particles move more erratically due to Brownian motion and get cau

Joey Henderson returns to the podcast to talk about heat pumps and inverters. The reversing valve, defrost cycles, and auxiliary heat can cause confusion for people who have primarily worked with furnaces or straight-cool A/C systems. Heat pumps use defrost cycles and bring on the auxiliary heat when the coil is ice-bound, which can present a challenge; we need to maintain cold coils without going into defrost all the time.  Even though heat pumps were significantly less effective in years past, we will still see reduced performance in very cold conditions with the newer inverter-driven systems. Proper design, installation, and commissioning will also help occupants get the best performance out of their heat pumps. Inverters offer plenty of advantages for the cooling aspect of heat pumps, too, especially when it comes to achieving longer runtimes for dehumidification. They can also float their coil temperature, much like how refrigeration systems can use floating suction or head pressure. Condensate assemblie

Joey Henderson joins the podcast to talk about airflow and how we can get air where it needs to go. Duct design is one of the subjects that fuel Joey's passion for HVAC. In many cases, people focus too heavily on the equipment when diagnosing airflow problems; sometimes, the equipment simply can't perform as it should due to a poorly designed duct system. In residential HVAC, many duct systems aren't adequately planned out, and the airflow can't overcome restrictions like filters. We also need to keep in mind that flex ducts need to be as straight and tight as possible, and it's usually best if we slightly upsize them (compared to sheet metal). Even though balancing dampers aim to solve airflow problems, they often lead to other issues when installed and used incorrectly. In many cases, proper duct design would solve problems without the need for balancing dampers. Bypass dampers are also commonly misapplied. Some technicians also aren't properly trained to position their static pressure probes appropriately

This podcast episode contains some of the questions and topics from the Business Round Table at the 4th Annual HVACR Training Symposium. Panelists include Tersh Blissett, Luke Peterson, and Andy Holt. One of the most critical parts of HVAC business ownership is knowing when to grow your business (i.e., hiring more techs and incorporating standalone maintenance and install departments). Ultimately, we need to think about how many service calls we're assigning to each technician per day and how many customers we have to turn down due to a busy schedule. Getting family members involved in the business can also have a range of positive and negative effects on a business. Delegating is another important skill that can help you run an HVAC business smoothly and focus on ownership and management over your day-to-day tasks. You need to understand your business's core processes but can delegate tasks that take time away from developing your business. When it comes to economic issues like inflation, we need to be looki

In this short podcast, Bryan goes over some information about cap tubes (capillary tubes) and flow facts. Cap tubes are metering devices; they're long tubes with small diameters, and their flow rates are dictated by the tubing diameter size and tube length. Pistons and TXVs are some of the most common metering devices in residential HVAC, and flow restriction doesn't just happen at the metering device; distributors also contribute to the pressure drop and act like small capillary tubes in addition to the metering device. Older units, simple refrigerators, and window units are more likely to have capillary tubes as metering devices, as cap tubes are an easy and versatile use of small-gauge tubing. The diameter is the primary factor that influences the flow rate, and length is usually secondary. However, longer tubes cause the fluids to encounter more resistance (in the form of friction) as they flow from one end of the tube to the other; the longer the tube, the lower the flow rate. Longer tubes also cause the

Jim Fultz and Jim Hagl from Copeland join the podcast to talk about filter driers and system cleanup. Filter driers come in many types and sizes; they typically go on the liquid line (bi-flow filter driers are used on heat pumps), but suction line filter driers also exist.  Copeland’s liquid line filter drier models include the EK (premium), BSL (smaller diameter), BOK (with HH desiccant to assist with burnout cleanup), and CU (copper spun). Bi-flow filter driers in Copeland’s lineup include the BFK and BSB categories. These liquid line filter driers protect the metering device and should typically be installed as close to the metering device as possible (with some exceptions for heat pump startups in heating mode). These filter driers typically need to be replaced anytime the system is opened for service, the pressure drop across the drier exceeds 3 PSI, or the system is wet.   Suction line filter driers in Copeland’s lineup include the ASD, SFD, and CSFD models, all of which come in different shapes and siz