Tech Tips

For those of you who use the MeasureQuick app for system diagnosis and performance testing, you may have noticed the “fan efficacy” results and wondered what it is. It is simply the CFM output of the system divided by the wattage used by the blower. It is only for the blower motor and has nothing […]

I've been reading a book called Cool: How Air Conditioning Changed Everything, and it got me interested once again in the history of air conditioning and refrigeration. Like many things, the people who are credited with “inventing” are the ones dogged enough to make an idea commercially successful, not the idealists forever tucked away in the […]

Photo Courtesy of Emerson What is Cascade refrigeration? “Cascade refrigeration” is a term you will hear more and more over the coming years, and while some of the systems may be very complex, the concept is actually pretty simple. Some refrigerants are well-suited for high and medium-temperature applications, and some are better suited for lower-temp […]

Connecting more than one wire on or under a single lug or connection point is called “double lugging,” and it is ONLY allowed in line voltage wiring under one condition, according to NEC 110.14: If the terminal, lug, or connector is specifically rated for more than one wire In the case of a conductor splice, […]

We all know (or should know) that venting refrigerant is a big no-no and can result in trouble from the EPA. There are many other potential violations, but two of them can easily occur if you aren't thinking ahead at the disposal of mercury and oil. Mercury is found in fairly large quantities in the […]

There was a story that came out recently based on an ASHRAE study performed by David Yuill from the University of Nebraska. The study appeared to indicate that condenser coil cleanliness makes no difference on system performance and efficiency. Those of us who have worked in the field know that coil cleaning matters because most […]

Today's tech tip is a video put out by my friend Brad Hicks from the HVAC in SC YouTube Channel. Thanks, Brad! Seal boots to prevent raccoon leaks. Ok, this has nothing to do with raccoons, but I like that photo. Whenever you are installing duct boxes (also called boots or cans) in an aftermarket […]

“Service factor” is an interesting motor rating that you will see on many motor data tags. It simply means how much additional “work” a motor can do or how much “load” it may be placed under for short periods of time without failure or overload. For example, the FLA or full load amps of the […]

There is a common belief in the trade that the higher the subcooling, the better the system efficiency because lower liquid line temperature means less flash gas. This statement is only partially true and can lead to some confusion among techs. Subcooling is a temperature decrease below the condensing temperature of the refrigerant that occurs […]