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Different Ignitor Types and How They Work
The VOCs Lurking Under Your Customers’ Sinks (and In Many Other Spots)
Another Ob-NOx-ious Combustion Product
How to Replace a Condensing Fan Motor
Design and Performance Challenges of Air-Source Heat Pumps Across Diverse Climatic Conditions
Brownouts and How They’re Killing HVAC Equipment
CAT Ratings on Electrical Multimeters
AHRI Performance Data vs. Manufacturer Expanded Performance Data (and When to Use Each)
Field Guide to Crankcase Heaters
Combustion vs. Compression – Short #275
HVAC In the Northeast w/ Leo & Paul Sharkey
Superheat in Heat Mode: Why Heat Pumps Get Weird – Short #274
What We Learned From NCI Duct / Balancing Training
HVAC Systems for Architects: Making Sense of the Alphabet Soup – Short #273
Sizing Breakers and Conductors (for HVAC) – Have Things Changed?
Absorption Cooling – The Rise and Fall and Rise – Short #272
Combustion Analysis w/ Tony G.
Residential vs. Commercial HVAC Sales
#hvac
Tech Tips:
In the furnace sequence of operation, the ignition sequence happens after the safeties have been checked, the inducer fan comes on, and the pressure switch closes. The ignition sequence begins with the ignitor. This part provides the heat needed for combustion (remember: a fire needs heat, oxygen, and fuel), and the ignition process looks a […]
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In HVAC, we have a few infamous indoor air quality monsters that bring terror to our customers’ homes—gases, particles, and organisms that wreak havoc on indoor air quality (and may contribute to moderate to severe health problems). The big one is carbon monoxide (CO), which we all know is deadly. Although not deadly by itself, […]
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As we do fall maintenance and head into the heating season, combustion analysis becomes a big deal. (It’s always kind of a big deal, but now it’s a really big deal.) First and foremost, it tells us how much carbon monoxide (CO) is produced by burning. CO can make people ill, contribute to cognitive deterioration […]
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Service calls about condensing fan motor failure are quite common. Even though fan motor replacement is a standard procedure for residential split systems, it requires careful attention to safety and detail. This article will give you a step-by-step guide showing how to replace a condensing fan motor. Along the way, we will also explain a few […]
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This tech tip was inspired by Alex Meaney and Ed Janowiak’s session at NCI’s High-Performance Summit 2025: “Good Design Isn’t a Buffet: The Importance and Interconnection of Manuals J, S, and D.” Alex is a building science expert who worked at Wrightsoft (now MiTek) for several years before launching his consulting firm, Mean HVAC Consulting […]
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HVAC technicians typically focus on diagnosing issues related to mechanical wear, refrigerant leaks, or control problems within the equipment. However, damage can also originate from external sources. For instance, a failed control board might be attributed to internal shorts or rubouts. Yet, the root cause could be external, such as the voltage spike that can […]
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If you have a multimeter for HVAC work, you most likely have a meter with a CAT III rating on it. Some might also be rated for CAT II at higher voltages or CAT IV at lower ones—or both, like this model of the UEi DL599 from our Multimeter 101 for HVAC 3D video. In […]
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Equipment selection may seem like a pretty straightforward process: look at the data plate, find the tonnage that’s close to your Manual J calculation’s total load, and you’re good to go, right? The problem with that approach is that a 3-ton unit won’t deliver 36,000 BTUs per hour like it says on the data tag. […]
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Crankcase heaters are a critical but often overlooked component in air conditioning and refrigeration systems. Their function is simple but vital: to prevent liquid refrigerant from migrating into the compressor crankcase during the off-cycle. A missing or failed crankcase heater is a leading cause of premature compressor failure. This guide covers why they're necessary, how […]
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Videos:
Podcasts:
In this short podcast episode, Bryan covers the history of the great heating debate: furnaces vs. heat pumps or combustion vs. compression. He also gives a breakdown of each other's strengths and gives his two cents on the winner of the debate. Fire kept humans warm for much of history, but engineers developed a […]
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In this engaging episode of the HVAC School podcast, host Bryan Orr sits down with Leo and Paul Sharkey, a father-son duo of mechanical engineers who made the leap into the HVAC business. Leo and Paul share their remarkable journey of purchasing an HVAC company in September 2020 and quadrupling its revenue within five […]
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In this short podcast, Bryan answers a listener-submitted question and explains why heat pumps get a bit weird: when it comes to superheat in heat mode. He also explains how we can move heat from outdoors to indoors, even in temperatures below freezing (cold temperatures just have less heat, not zero heat). In order […]
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In this engaging and informative episode, Bryan sits down with Elliot to discuss his recent training experience with the National Comfort Institute (NCI), covering two intensive courses on duct system optimization and residential air balancing. The conversation offers valuable insights for HVAC professionals looking to improve their technical skills and provide better service to […]
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In this short podcast, Bryan answers a question submitted to HVAC School by an aspiring licensed architect who wanted to learn more about the many different types of HVAC systems. The three main buckets of HVAC systems are air-to-air, water-source, and air-to-water. Air-to-air systems move air around to remove heat from one space, and […]
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In this essential episode, Bryan Orr sits down with Elliot, the residential install supervisor at Kalos Services, to unpack a critical issue that's causing confusion among HVAC technicians, electricians, and inspectors alike: the new standards for breaker and conductor sizing on inverter-driven equipment. The conversation was sparked by Elliot's frustrating experience of having two […]
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In this short podcast episode, Bryan goes on another history journey, retelling the story of the rise and fall and rise of absorption cooling. Some of the first HVAC/R engineers cooled buildings with fire; they used absorption refrigeration, which ran on heat instead of electricity. In the early 1800s, French scientist Michael Faraday showed that […]
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In this comprehensive training session from the symposium, Tony Gonzalez, Training Director at Fieldpiece, delivers an engaging and practical guide to combustion analysis for HVAC technicians. With 25 years of experience at Fieldpiece—from warehouse worker to training director—Tony brings both technical expertise and real-world application to this 50-minute interactive session focused on the company's […]
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In this candid conversation, Nathan and Bryan dive deep into the often-misunderstood world of sales in the construction and HVAC trades. Nathan, who has transitioned from fieldwork to spending roughly 60% of his time in sales, offers a unique perspective on why sales professionals are necessary despite the skepticism they face from tradespeople. The […]
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