HVAC School - For Techs, By Techs

In this free-flowing conversation, the Trethewey family talks about growing up with This Old House, what the show is like behind the scenes, what Rich misses about the past, what the future holds for the trade, and some nerdy specifics between Bryan and Ross. The show business is a collaborative effort between the producers and talent (even though they're real people, not actors), and the Trethewey boys find the end result almost cathartic. This Old House was never scripted; there were beats and predictions about the content, but the content is all authentic. As the trade moves forward, Richard worries about weakening connections and producing leaks in the race to improve technology. He's glad that we work with far fewer deadly chemicals and materials nowadays, though. Many technicians are artisans at heart, and the future is bright because of techs who make ethical choices and do good, aesthetically pleasing work. (However, we can expect controls and ventilation to become increasingly important in coming years.) Bryan and Ross also brainstorm some innovative solutions for residential applications by looking at commercial equipment. Bryan enjoys thinking about using R-290 chillers and buffer tanks for residential applications. Ross anticipates a future focus on CO2 as a residential refrigerant; he thinks the future "magic box" solution is a CO2 split system for heating and cooling. Richard, Ross, Evan, and Bryan also discuss: Exposure to media Propane refrigerant Heat pumps vs. natural gas Hydronics Staying organized Pit corrosion on copper pipes What it means to be an "expert" at something and how it feels Core traits of successful skilled tradespeople Passive makeup air solutions New control strategies Getting new people into the trades   Thanks to Richard, Ross & Evan for making this happen. Check out the This Old House podcast “ClearStory” on your favorite podcast player. You can also learn more about the Trethewey boys' work at TE2 Engineering and RST Thermal. 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. TE2 Engineering    RST Thermal

Two of the great air and infiltration expert minds of our time, Gary Nelson and Steve Rogers from TEC (The Energy Conservatory), come on the podcast to talk about blower doors. They also discuss blower door testing and how it compares to real-life infiltration. A blower door has a fan to measure the air flowing through it, and you generally install it in a doorframe. Blower doors hook up to manometers to measure the pressure differential between the inside of a building and the outside. Generally, you need to adjust the fan speed to bring the pressure differential down 50 Pascals. Then, you measure the airflow through the blower. That is how you determine how leaky a building is; all the leakage comes out through the blower door due to the pressure differential. We use blower door data and mathematical models to estimate the natural infiltration rate. ACH50 is a means of expressing the leakage (air changes per hour at 50 Pascals). You take the CFM50 and multiply that by 60 to get the cubic feet per hour. Then, you divide that product by the cubic feet of the building to get your ACH50. You can apply a similar process to the surface area of a building instead of volume (though that's more common in commercial buildings). During natural infiltration, the leaks can move inside or outside the envelope, so it's difficult to use the blower door test to measure infiltration accurately. Wind and extreme temperatures also affect natural infiltration, and testing can't account for those. Gary, Steve, and Bryan also discuss: Testing pressure variations Analogies for measuring infiltration at 50 Pascals PSIG vs. PSIA Stack effect CO2 and infiltration Predicting infiltration rates with models Infiltration in cold climates How infiltration affects the latent load Duct leakage and building pressure Transfer grilles Balancing with precision manometers   Check out The Energy Conservatory at energyconservatory.com. 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 how to keep your humanity and make moral decisions when selling IAQ products. As the COVID-19 pandemic has started to grab hold of the world, we've seen an uptick in IAQ interest. When you have greater consumer interest, there are opportunities to hoodwink customers. While some IAQ products are indeed not very effective against viruses, there are some good products that you can sell to customers to benefit their health. Pretty much every product has an appropriate application, but sales and marketing can lead to inappropriate, ineffective usage. Some techs sell IAQ products for inappropriate applications just to make a buck, but many others simply don't know any better. For example, UV and PCO technologies can work very well for certain applications, but they are not the fix-all that some people market them as. When selling IAQ products honestly, you'll want to understand the efficacy data in the exact application you're selling it for. If you don't have the data for the application, don't make claims about efficacy. When it comes to oxidizers, you must also be transparent about safety concerns. Sure, you can explain how particles combine, but you also have to explain safety issues with the particles' behavior. Independent testing is also important. Paid studies can be manipulated to make a product look favorable. Ask if the product does what it's supposed to do. Then, you have to ask if the product is safe. Cold plasma and oxidizing products are a bit less effective than other PCO technologies, but they are a bit safer. The goal is to educate yourselves and the customer so that you can both make the best decision for the customer's health.   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.

Nikki Krueger joins us to talk about how humidity impacts indoor health and some ways to make our indoor air quality better (for real). Indoor air quality is all about manipulating the air in our homes to reduce pollutants and keep our air quality high. From air dilution to running bath fans to air purifiers, there is a lot more we can do to make our homes healthier. We can't entirely isolate ourselves from viruses, bacteria, and fungi. However, there are many other things inside our homes that can suppress our immune systems, and we can address some of those things with IAQ. To incorporate humidity control into our plans, we must look at the dew point. Dew point will change across the country and throughout the seasons, so we must work with varying conditions to keep RH in the 30-60% range. You can run kitchen and bathroom exhaust fans to manage moisture and VOCs. However, we also have to make sure the air we draw in is high-quality and won't upset people's allergies. So, ventilating dehumidifiers are an attractive option to replace exhausted air with high-quality fresh air. Temperature is mostly about comfort instead of health, but filtration, ventilation, and humidity directly impact the healthiness of our indoor environments. When we can control those three things, we can create indoor environments that are truly healthy. Ultra-Aire dehumidifiers can tackle all three of those, but education and holistic thinking are the real solutions to healthier homes. Nikki and Bryan also discuss: Air dilution Long-term payoffs The tricky IAQ puzzle in multi-family buildings Building design and IAQ Talking to customers about ALL options The "dehumidifier graveyard" What makes Santa Fe Ultra-Aire unique   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, Sal Hamidi of ProductsByPros joins Bryan to discuss what manometers are and how they measure pressure. Manometers measure pressure at a much higher scale than a micron gauge but lower than that of a pressure gauge; they measure pressure differentials by comparing static pressure to another source of pressure as a reference. Across all segments of the industry, we use manometers to measure static pressure. Static pressure is the pressure of air against the duct, not the actual air velocity. (Static pressure can give you an idea of the airflow, but you need pitot tubes or flow hoods to measure the actual airflow.) We can also use Magnehelics to measure static pressure, but it's just a specialized type of manometer. We can also use manometers in conjunction with blower doors to perform zonal pressure diagnostic tests. Blower door tests require the technician to pull the house pressure down to -50 Pascals. Then, the technician uses a very precise manometer to help determine the air changes per hour (ACH). Manometers are also invaluable tools in markets with lots of gas furnaces, as they measure gas pressure. You measure gas pressure on the inlet AND outlet side of the gas valve to make sure the pressures are correct. Every tech should have a regular manometer for everyday use to measure static or gas pressure. Techs on the building science side of the industry should have a precision manometer, which is an expensive but very precise instrument. Sal and Bryan also discuss: Pressure scales (in wc., PSI, Pascals, etc.) Absolute vs. relative scales Accuracy, precision, and resolution   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.

Michael Housh and Jim Bergmann join Bryan to look into the crystal ball to see the future of air conditioning and design the PERFECT residential system. Self-contained propane heat recovery chillers are futuristic devices that do simultaneous heating and cooling. While they may not be suitable for all climates, they can switch between heating and cooling modes, like heat pumps. They may also be able to service domestic hot water centrally as well. Although propane heat recovery chillers are impractical for residential use right now, they could hold the key to the future of air conditioning. Geothermal systems sound like a great energy source in theory, but the cost of installation may not be worth the investment for many homeowners. You only get payback on geothermal when it's time to replace the unit, so it takes a long time to recoup your initial expenses. While these systems may work well in northern climates, you won't see many geothermal systems in the South. Even though some customers have personal convictions about saving energy and efficiency, cost, effectiveness, and maintenance are going to be the most important factors to most homeowners. One of the challenges to adopting new technology is the lack of knowledge of new technologies. We expect a lot out of technicians when it comes to knowing how components work and what they do. When we introduce technology-heavy new systems, it can take a long time for technicians to become proficient with those technologies. Michael, Jim, and Bryan also discuss: Pool heating Equipment ROI Solving the flammability problem of R-290 Radiant heating and cooling Heat exchangers and piping resistance Pre-conditioning outdoor air Niches in the industry Ice banks New flammable refrigerants   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.

Thomas Talhelm, the founder of Smart Air, joins Bryan on the podcast to talk about how a filter and a fan in China sparked an IAQ revolution. The simple device changed his thinking about air purification. As a graduate student in China, Thomas witnessed the Beijing "Air-pocalypse" firsthand. That was when he became aware of the issue of air pollution and the potential health issues it can cause. So, he dove into the world of air purification. The most popular air purifier on the market was about $1,000, but Thomas felt that the price tag was way too high for protecting human health. Instead, Thomas decided to make his own air purifier with just a filter and a fan. He bought a laser particle counter to test his DIY air purifier and began publishing his data to make his health and safety data accessible and make cleaner air available to everyone. So, the goal of Smart Air is to lead an IAQ revolution by educating others about air pollution, sharing data about IAQ products, and improving health. The goal is NOT to earn lots of money. Thomas also uses his own experiments and data to answer tough but practical questions. For example, he has done studies to discover if indoor or outdoor air is cleaner. (Of course, the answer depends on location, but it's still a question that we've needed to ask for the sake of consumer health.) However, educating consumers and being transparent about the data requires a delicate balance of marketing and communication. Thomas and Bryan also discuss: Social enterprises vs. non-governmental organizations (NGOs) Smart Air in international markets COVID-19 and masks Being a researcher/professor Organizing data Sharing data in workshops The future for Smart Air   Check out Smart Air at smartairfilters.com. 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 the steady-state voltage problem that can take out inverter boards and what to do about it. Inverter-driven equipment refers to a variable-frequency drive with ECM compressors and fans. We're talking about modern split-phase equipment rated for 208v or 230v power. However, the split-phase power will yield 240v. Most motors and components for 240v equipment have ratings for 230v AC power. L1 and L2 power can also be significantly higher than 240v, sometimes going as high as 250v. Inverter boards have a widespread failing problem in locations with high steady-state voltage. Surge protectors only work for spikes in voltage, such as lightning strikes; they don't protect equipment from steady-state high voltage. Inverter boards are rated for 10% voltage over 230v and 5% lower than 208v. The operating range is 197-253v, but consistent overvoltage that doesn't quite reach 253v can still lead to failure. We attempted to fix the problem by using the ICM493. These protectors have single-phase monitoring and have a NEMA 3R rating (suitable for outdoor usage). You can set the high and low voltage limits and get the benefits of thermally protected MOV surge protection. Although the inverters stopped failing, they started shutting off when they weren't supposed to. We discovered that the power companies were allowed to run up to 252v, which was right on the limit! Power companies may also run voltages 1-2v higher than 252v, so that explained the failures and shutoffs. If you decide to use the ICM493, you need to calibrate the voltage based on measured voltage (such as from a voltmeter). Then, you set it for 230v +/-10%. If you experience recurring problems with overvoltage, the power company probably won't be much help. In that case, you can use a buck-boost transformer.   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.

Jim Bergmann and Michael Housh join Bryan to talk about testing A/C vitals. They discuss the new vitals mode in MeasureQuick and how it works. As with many of MeasureQuick's other functions, vitals mode is an invaluable tool for green and experienced HVAC techs alike. The new vitals mode helps us with charging, airflow, and other staples of A/C testing and commissioning. Vitals mode allows the user to give MeasureQuick some information about the system; when they provide that information, MeasureQuick can instruct them to use the most appropriate charging method. When you add enough refrigerant to create a liquid seal, you will begin to see a temperature drop across the evaporator. At that point, MeasureQuick would inform the user to stop charging and raise the airflow. MeasureQuick's vitals mode guides the user through the commissioning process by focusing on the main drivers: airflow and charging. The app also focuses on secondary drivers, including low-pressure, high-pressure, superheat, and approach. You can get to vitals mode by hitting the "trending" button twice. At the bottom, you can start with the quick charge; you then choose your refrigerant and the charging method. Vitals mode can help several new techs during the cooling season. The weigh-in feature helps prevent overcharging, which is a problem that's all too common. MeasureQuick has been working to fill the gaps in training by helping technicians do jobs correctly and avoid the confusion of listening to many different senior techs or trainers. Jim, Michael, and Bryan also discuss: Subcooling and line length Approach Sensible capacity vs. latent capacity Target temperature split Superheat Trade school vs. field training for charging Increasing the quality of HVAC instruction   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 how to use liquid line temperature as a quick diagnostic indicator on split A/C systems. Liquid line temperature is one of the first things to check when you approach a system. Checking that temperature is also a great way to get into non-invasive testing. The temperature should be between 4 and 15 degrees warmer than the outdoor temperature (unless it is wet). If the liquid line is cooler than the environment, then there could be a restriction. If there is a restriction, you could have a clogged liquid line drier or a partially closed service valve. When you have a larger condenser coil in relation to your capacity, your liquid line will be closer to the ambient temperature; the refrigerant must be at a higher temperature than the outdoor air to give off heat. You should also not see a pressure drop across the liquid line. An important value is the condensing temperature over ambient (CTOA). On a normally operating piece of equipment, the condensing temperature will be 15-30 degrees above the outdoor temperature. The CTOA is a design feature that sets the differential between the saturation temperature and the ambient temperature. So, before the refrigerant subcools, it will be 15-30 degrees above the outdoor ambient temperature. Subcooling goes below the CTOA. If we have a 30-degree CTOA and subtract 10 degrees of subcooling, then our liquid line will be about 20 degrees above the ambient temperature. If you add up all the numbers and find that the liquid line is warm, then you likely have an airflow restriction (dirty condenser, etc.). You shouldn't see a temperature differential across the liquid line; if you see one, then you likely have a restriction in the liquid line or lines that are too long.   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.