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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
What Makes a Thorough Comfort Consultation
Compressor Failure: Diagnosis and Replacement Checklist for Residential and Light Commercial Equipment
Legionnaires’ Disease: The Cooling Tower Killer – Halloween Short #263
Group Training – What We Have Learned
How Air Conditioning Saved the Movies – Short #262
Just Do it! w/ Chad Simpson
Analyst vs. PM vs. Operations – Short #261
The Hidden Cost of Killing Radiant Load – Short #260
Balance Point Explained w/ Jim Fultz
Dehumidify with a Waterfall? – Short #259
What are User Requirements? w/ ELK
#hvac
Tech Tips:
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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This tech tip is based on an HVAC School podcast episode with Tim De Stasio. Tim has written several articles about HVAC design on his blog, several of which he has been generous enough to share with HVAC School. Tim’s focus is on humid climates, and moisture mitigation is one of his main focuses in […]
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Special thanks to Ty Branaman and Bert Testerman for their work and feedback on this tech tip about compressor failure diagnosis and replacement. A PDF checklist that covers all of the procedures in this tech tip can be found at http://www.hvacrschool.com/compressor-replacement-checklist. Important Note Before You Begin Industry data indicates that up to 30% of compressors […]
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Videos:
Podcasts:
In this spooky Halloween short podcast episode, Bryan tells the story of the cooling tower killer: Legionnaires' disease. In the summer of 1976, the nation celebrated its bicentennial anniversary. The American Legion was holding its 58th annual convention at the Bellevue Stratford Hotel in Philadelphia, PA. In the days following the convention, doctors in […]
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In this episode of the HVAC School podcast, Bryan Orr sits down with Bert and Leanna to discuss Kalos's first official cohort apprenticeship program, dubbed the “Launch Program.” What started as Bryan's persistent idea—one that the team initially resisted as too expensive and logistically challenging—evolved into a transformative three-month training experience that brought 15 […]
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In this short podcast episode, Bryan explores an interesting story in the history of HVAC: how air conditioning saved the movies. In the summer of 1925 in NYC, a new film was set to appear on the big screen… but the theater was stuffy with no fan that could cool down the sheer mass […]
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In this candid conversation recorded live at the NCI Summit in Austin, Bryan Orr sits down with Chad Simpson, owner of Simpson Solutions, for an unexpectedly revealing discussion about the reality of building a successful HVAC business. What makes this episode particularly compelling is Simpson's refreshing honesty about his struggles, failures, and the gradual […]
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In this short business-oriented podcast, Bryan breaks down the differences between three commonly confused positions/roles: analyst vs. PM (project management) vs. operations. When you own or work in a small business, you might wear a lot of hats: estimating, writing proposals, troubleshooting, being a customer or coworker's therapist, etc. This work can be organized, […]
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In this short podcast, Bryan talks about the hidden cost of killing radiant load, especially when it comes to installing radiant barriers in attics. We sometimes get service calls about ducts sweating when they never used to sweat. If there are no problems with the system (i.e., the refrigerant charge, static pressure, airflow, supply […]
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This comprehensive episode dives deep into one of the most critical yet misunderstood concepts in HVAC: balance point calculations for heat pump systems. Jim and Bryan break down the complexities of dual fuel systems, explaining why proper sizing and balance point calculations are essential for both comfort and efficiency. The discussion moves beyond basic […]
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In this short podcast episode, Bryan talks about history and HVAC science: how to dehumidify the air with a waterfall and how cold water became the first air conditioner. In 1902, Willis Carrier worked for a printing company in Brooklyn, New York. There was a huge humidity problem during the summer: the printing plant […]
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In this comprehensive session, Eric Kaiser walks through the critical importance of establishing proper user requirements before making equipment purchases. Drawing from real-world experiences in the HVAC industry, he demonstrates how poor upfront planning leads to costly mistakes, buyer's remorse, and multiple equipment purchases. The discussion covers everything from selecting simple tools like screwdrivers […]
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