Fenestration is a fancy architectural term that means “openings in the outside of the building.” You will see this word a lot when you read ACCA manual J or when you are doing a manual J load calculation. Fenestration loads include heat losses and gain through windows, doors, skylights, etc., and they can make up […]

This article is an extension of HVAC School’s “How to Measure Gas Pressure” video. Additional input was provided by Jim Bergmann. Bubble test procedures and standards were provided by Honeywell. Links to source materials are available at the end of this article. If there’s one complaint that HVAC techs should never take lightly, it’s a […]

We had a class with our refrigeration techs, and the topic of leaking and bypassing service “angle” valves and ball valves came up. One of the techs pointed out that most valves recommend loosening the top nut on ball valves and the packing nut on angle valves before turning the stem for maximum longevity of […]