In HVAC, we rarely need to have a deep understanding of electrical design. But there are a few cases where a little understanding can go a long way in identifying issues before they cause trouble, and that is the intent of this short article.
Evacuation is often called “vacuum” or “pulling a vacuum,” and it’s one of the most important parts of the HVACR installation and repair process where the refrigerant circuit is involved. Our goal should be to keep the closed refrigeration circuit clean, dry, and tight — just like I was taught since the very first week of HVAC school.
Yesterday I walked up on one of our managers who was talking to a junior tech diagnosing an intermittent controls issue on a pool heat pump.
In the background, you could hear an extremely loud compressor.
If you are making a refrigerant circuit repair, weighing out and weighing in makes perfect sense, especially since microchannel condensers and scroll compressors make pumping down less viable anyway. But there are many cases where you just need to check the charge to make sure the system is working properly, and in these cases, weighing in and out is just plain silly.
When the liquid temperature (liquidus) of the alloy (rod or wire) you are using is 840°F or lower, the process is considered soldering. Brazing occurs when the liquid temperature of the alloy is above 840°.
For the quick, cut to the chase version, turning the adjustment on the bottom of an adjustable valve clockwise equals higher superheat while turning it counterclockwise equals lower superheat. However, before you start messing with the adjustment, I suggest you read on.
Before we convert temperature scales, let’s take a step back and think about what temperature is in the first place.
Temperature is proportional to the average kinetic energy of the random microscopic motions of the constituent microscopic particles, such as electrons, atoms, and molecules.
I live in Central Florida, and while it can get pretty hot in the Summer we also tend to get afternoon thunderstorms that come and go in a flash. I have been connecting gauges, checking charges and even pulling vacuums in the rain as well as under umbrellas or cardboard boxes most of my career and only recently did I stop to think if this was a good idea.
I see techs in the field get the most frustrated when they have a low-voltage short they can’t seem to locate. The challenge techs face with low voltage diagnosis is a combination of poor process and some root misunderstanding about what they are looking for.