I was listening to someone talk about air relative humidity the other day while looking at a psychrometric chart, and he commented that the chart ends down at freezing (32°F) because “all the water freezes out of the air at that point.” I think I made this Jed Clampett face: The psychrometric chart is designed […]

Since I started in the trade, we would take discharge line temperature in the winter on a heat pump system. You can easily check the discharge line in the winter, while suction superheat and even subcool can be more difficult to access. The old-timers who trained me would say that the discharge temp will be […]

In residential air handler/fan coils, it is common to use a high-voltage interlock between the blower and the electric heat strips to ensure that the blower comes on whenever the heat is on. The problem is that it CANNOT work the other way around where the heat comes on with the blower. Heat strips are […]