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Two Ways to Prevent Freezing in 90%+ Furnace Condensate Lines
Decoding Measurement Lingo
History of Thermometry and the Invention of Thermometers
It’s All Relative… Humidity
The Heating Sequence of Operations and Onions
Electronic Expansion Valve Troubleshooting
The Best (and Worst) Ways To Duct a Dehumidifier
The Evolving Career of the HVAC Contractor: Embracing Change to Stay Ahead
How To Do a Heat Maintenance That Actually Matters
Standing Pilot – Short #228
History of Gas Furnaces – Redux
Heat Exchangers and Temperature Rise – Short #227
Manufacturer Responsibility – Manifesto
Q&A – Tips for Moving to HVAC Sales – Short #226
White Shirt Techs – Manifesto
Q&A – Double Flares – Short #225
Can You Coat Fiberglass?
Redux – The Lost Art of Steam Heating w/ Dan Holohan
#hvac
Tech Tips:

This tech tip came from an email sent by Adam Blunkall, a Tennessee-based HVAC technician. He shared some tips to help overcome this issue in his market, and we appreciate his insight. Thanks, Adam! If we’re draining our 90% furnaces (or any condensing heating system) outside the structure in a similar fashion as we would […]
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Troubleshooting and commissioning are entirely data-dependent processes. How can you know that a system is undercharged unless you measure the superheat and subcooling? How can you know how much static pressure a blower motor has to overcome? In both cases, we use tools to help us determine the next steps. However, using the right tools […]
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So, what is thermometry anyway? Thermometry is the scientific study of measuring temperature and has roots that date back to as early as 220 BC. During this time, Philo of Byzantium began to study the effects that temperature had on air. Specifically, he observed expansion and contraction caused by temperature change. He did this using […]
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Florida’s got a lot of great qualities: some pretty neat wildlife, beaches all around, and theme parks. On the flip side, Florida also has hurricanes and a lot of humidity. As much of a pain as it might be for residents and contractors alike, humidity is one of my favorite topics. We see relative humidity […]
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Just like Shrek, I like to think about the heating sequence of operations as an onion—it has layers. And each layer builds upon the previous one. We have written previously in great detail about gas furnaces, from top to bottom. I want to focus today on why there is a sequence of operations and how […]
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Electronic expansion valves (or EEVs) are metering devices that you’ll find in a variety of modern HVAC equipment, including heat pumps, VRF units, inverter mini splits, and chillers. This valve is electronic rather than mechanical and can precisely control the flow of refrigerant into the evaporator and optimize efficiency for heating and cooling units. Other […]
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There are a couple of really important things to understand when ducting a dehumidifier. Getting one or both of these things wrong can throw off your entire dehumidifier install. Instead of just telling you the different ways you can install a dehumidifier, let’s talk through some dehumidifier basics, which will help us understand why it’s […]
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This tech tip was written by Shelby Breger, co-founder of Conduit Tech. You can check out everything Conduit has to offer and learn more about that interesting platform and how it helps contractors at https://getconduit.com/. Thank you, Shelby! Before starting Conduit Tech, Marisa and I spent a year doing everything we could to learn about […]
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I know I’m not the only one who has sometimes felt a little bad doing heat maintenance. I remember many a day when my lead technician and I (as an apprentice) would crawl into an attic, clean the flame sensor, and then play FarmVille on our phones for 15 minutes before crawling down, giving the […]
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Podcasts:

In this short podcast episode, Bryan talks about the standing pilot gas systems and the ignition strategy in gas-fired appliances. Standing pilots are very simple devices that are common in fuel logs, water heaters, and some pool heaters. These devices have a thermocouple or thermopile; in a thermocouple, two dissimilar metals are connected at […]
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Jim takes us all the way through the history of furnaces, from the Stone Age when he was a child to modern modulating condensing types. The goal of a furnace is to move heat, so a furnace uses heat exchangers to facilitate heat transfer. Furnaces have primary and secondary air. The primary air goes […]
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In this short podcast episode, Bryan talks about heat exchangers and temperature rise in gas furnaces, especially 80% open-combustion gas furnaces. Temperature rise is the difference between the return air temperature and supply air temperature; in cooling, we usually refer to this difference as a delta T or temperature split. The manufacturer sets a […]
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In this episode of the HVAC School podcast, Bryan shares his “Manufacturer Responsibility Manifesto,” a document he wrote over two years ago but held back from publishing until now. The manifesto addresses growing concerns about the burden being placed on HVAC contractors, particularly smaller businesses, due to manufacturing quality issues and warranty policies. The […]
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In this short Q&A podcast episode, Bryan answers a listener-submitted question and gives some of his tips for moving to HVAC sales from field technician/installer roles. The world of sales has a different pay structure, which makes it an appealing option to many technicians. Salespeople need to be able to have money conversations with […]
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This unique podcast episode is a commentary on the phenomenon of “white shirt techs” in the HVAC industry – a term that refers to technicians who focus heavily on sales and maintaining a pristine appearance rather than technical expertise. While there's nothing inherently wrong with having good sales skills or maintaining a professional appearance, […]
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In this short podcast episode, Bryan answers a listener-submitted question about double flares and their application in the HVAC/R industry. Flare connections are common in certain types of equipment, and they connect the copper to the appliance. As a result, when we make a flare, our goal is to make it leak-free. A regular […]
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In this episode of the HVAC School Podcast, Bryan interviews Zach about duct coatings and their applications in HVAC systems, particularly focusing on the Hardcast RE500 product. The discussion delves into the importance of proper duct coating applications and their benefits for both contractors and customers. Zach, who has extensive experience in duct cleaning […]
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In today's podcast, Bryan talks with legendary Hydronics author and trainer Dan Holohan about the history of steam heating and some practical applications of old ideas. Recently, Dan has been working on more novels, having published two of them over the past few months. Steam heating is a “lost art” nowadays; it has become […]
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