Why (and When) Do We Need Defrost?
Why Defrost? Let's start with the basics and move on from there. Defrost is necessary when the coil temperature drops below 32°F. Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or for just parts of […]
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Sweeping with Nitrogen
Two days prior to this article being published I sent one out about the popular fallacy that nitrogen “absorbs” moisture. That tech tip went out at 7 PM eastern time like usual, and I was sitting on the couch watching something on the Food network (like usual). At 7:10 PM I get a call on my cell […]
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Fan On or Fan Auto
Full disclosure, as a technician I was guilty for many years of setting the fan to “on” at the thermostat. I never really thought of any of the negative impacts that could happen. I wanted to circulate the air and to keep air moving through the high-efficiency air filter that most of our houses had. […]
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Air Velocity Quick Tips
Recommended Duct Velocities (FPM) Duct Type Residential Commercial / Institutional Industrial Main Ducts 700 – 900 1000 – 1300 1200 – 1800 Branch Ducts 500 – 700 600 – 900 800 – 1000 As a service technician, we are often expected to understand a bit about design to fully diagnose a problem. Duct velocity has many […]
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3 Bad Techs That Don’t Know It
First, let's state the obvious and clear the air a bit. The photo above is SUPER CHEESY! But this story is about three bad techs who don't know it so three models clearly posing in clean clothes makes as good of a proxy for a bad tech as anything else. First off, I'm not being negative […]
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False Alarms: The Legacy of Phosgene Gas
We’ve all been in the unenviable position of unsweating a compressor and getting blasted in the eyes with a waft of gas that smells like burning sulfur from the pits of Hades. As we stagger back, covering our nose and holding our breath, memories of the phrase “phosphene gas” from trade school or World War […]
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History and Basics of Refrigeration
Pioneers of refrigeration The modern world is impossible to imagine without refrigeration. The Internet, food transportation, medical imaging, and vaccine research, such as COVID-19, relies on refrigeration to function. Even the sprawl of cities across the American south in the 1950s was inconceivable without refrigeration and air conditioning. So if you like vacationing in Vegas […]
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Some Furnace Questions
I received an email from a podcast listener with some furnace related questions. Based on the nature of the questions I figured it would be better to ask an experienced furnace tech. Benoît Mongeau agreed to help by answering the questions.  My name is Matt and I am a newer tech (fully licensed this September, have […]
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Multi-Position Service Valves
This tech tip video comes from my friend Andrew Greaves of AK HVAC and HVAC Comedy on Youtube and the HVAC Vehicle Layouts group on Facebook. Many residential techs get confused when they see these multi-position valves in larger equipment and Andrew does a great job of demonstrating the basics in this video. In the […]
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