The chart above is from a Carrier heat pump, and it lists some common accessories. I have heard this common pressure switch (last on the list) called a low-pressure switch (because it opens on fall in pressure) and a high-pressure switch (because it's in the liquid line), but RARELY do I hear it called its […]

Here's the first question: Does it really matter if the speed taps on a motor are run or common? Well, yes… sort of. In some cases, it helps to identify if you're dealing with an open winding or an open thermal overload. The thermal overload breaks common, but you will still read a path between […]

  I walked into a supply house the other day and looked at a “universal” expansion valve on the shelf. The friendly guy behind the counter saw me and walked over. After saying hello, he said: “That's a great valve; it's even balanced port.” Now, I am a bit of a troublemaker. I should have […]