Sizing Return Grilles
A few weeks ago, I spent several days redoing a duct system and replacing a furnace for a friend. I had static pressure readings from before the system was replaced, and with the new furnace that I had picked out, I had created a static pressure budget and felt confident I could significantly lower the […]
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Under Pressure
A few weeks ago, I was hired to consult on a multi-family new construction project.  The building was already framed, and the ducts were roughed in.  The owner of the building was concerned with the quality of the ductwork.  He noticed that the HVAC company was not following the mechanical engineer's plans. This was my […]
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Refrigerant Recovery Practices
Recovery is the removal of refrigerant from a system. From there, you can either store it and send it in for recycling or reintroduce it back into the same system. Here are some top tips: Make sure your tank is empty and evacuated to 300 microns if you plan to return the refrigerant to the […]
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Common Causes of Compressor Failure
This article was written by Don Gillis, the technical training manager at Chemours. Thanks, Don! Refrigerant compressors are essential components of air conditioning and refrigeration systems, as we all know. They work by compressing refrigerant vapor, which then flows through the system and changes state as pressure and temperature conditions rise and fall. Unfortunately, these […]
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Training: Processes or Apprentices?
“It is only through the enforced standardization of methods, enforced adoption of the best implements and working conditions, and enforced cooperation that this faster work can be assured. And the duty of enforcing the adoption of standards and enforcing this cooperation rests with management alone.”  —Frederick Taylor “The objective of education is not to fit […]
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Sales: Techniques or Values?
“The very substance of our existing which has made us leaders in technique, stands as a barrier to any thinking which might be able to comprehend technique from beyond its own dynamism.” -George Grant The odd quote above takes some time to understand but has been rattling around in my brain for weeks now. George […]
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Troubleshooting with DTD
The temperature of the refrigerant in the evaporator coil can really help us with diagnostics, but we need to know the targets we’re aiming for if we want to get the most out of it as a troubleshooting tool. If we take the return air temperature and subtract 35 degrees from that number, we get […]
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Improving Humidity Control on the Cheap
This tech tip was submitted by Steve Rogers, the current president of The Energy Conservatory (TEC). Steve has been on the podcast several times in the past and is a valued contributor to HVAC School. Thanks, Steve! As summer approaches, HVAC technicians all over the US are preparing for those difficult conversations with occupants about […]
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Equivalent Length Merry-Go-Round
I recently read a tech tip by Matt Bruner about using the Manual D process. In the article, he designed a duct system for a small job using a ducted mini-split. One thing I noticed about his design was that the supply and return duct velocity was fairly low compared to the arbitrary 900-feet-per-minute supply […]
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