#pressure

We recently received a Speakpipe question for the podcast about a common nuisance call on straight-cool A/C units and heat pumps. The systems, often retrofit units, were backing water up into the secondary drain pan and overflowing it. This issue isn’t happening on furnaces, which are positively pressurized, which means we have to take a […]

About a month ago, one of my techs went on a “no heat” call. The house is a rectory for the church next door. The call came in, and after he ran it, I assumed the problem was solved since I hadn’t heard otherwise.  A few weeks later, they called back, saying the boiler was out […]

This article was submitted by Genry Garcia of Comfort Dynamics, Inc. It is the first part of his series on zonal pressure diagnostics. Thanks, Genry! Zonal pressure diagnostics have been around for a while. Here is a brief description of ZPD from the website redcalc.com:  Formerly known as the “Blasnik methods” in a nod to […]

    Everyone in the HVAC/R trade uses some type of torch to braze or solder alloys together. So, what is the proper way to handle an oxyacetylene torch? It turns out that there’s more than one right answer. Depending on which torch rig you use, the manufacturer’s manuals for operation may vary.  Everyone (hopefully) knows […]

Low pressures are often measured in inches of water column or “WC. Like most units of measure, it has a very simple origin; in a water manometer, 1″ of water column is literally the amount of force it takes to raise the column of water by 1”. While some water manometers (water tubes) are still […]

This article was written by my buddy and Canadian Supertech Tim Tanguay. Thanks, Tim! This P/E chart shows R410a at 100°F saturated condensing temp, 10°F SC, 40°F saturated suction temp, 20°F SH at the compressor. The green highlighted thumb shape is the saturation zone. Everything that occurs in the saturation zone is a latent (change […]

The gas laws. We all learned about them in school and promptly forgot all about them. I really think that we need to dig our books out, dust that information off, and work to understand and apply it. Many will say that nitrogen pressure doesn't change with pressure like other gasses. That is false, but […]

 In this episode of the HVAC School Podcast, host Bryan Orr speaks with Chris Hughes of The Energy Conservatory (TEC) about using the Roomulator card and DG-8 manometer for room pressurization testing. Chris provides background on how he came up with the idea for the Roomulator. He wanted an easy way for technicians to […]

 In this short podcast episode, Bryan covers the differences between absolute and gauge pressure, as well as measuring pressure with a micron gauge or a manometer. Compression ratio deals with absolute suction and absolute discharge pressures. Absolute pressure requires us to add atmospheric pressure to the gauge pressure. We usually measure gauge pressure in […]