In our approach to humidity control for air conditioning systems, we must not overlook one very basic fact: If the evaporator coil is not cold enough, it cannot remove moisture, and it will stop removing moisture at its dewpoint temperature.
Manufacturers purposely design condenser and evaporator coils to work together in order to provide the best possible cooling for an application. So why would anyone consider replacing one coil and not the other? Why would anyone be tempted to oversize or undersize one component when the other isn’t designed for that capacity?
Potential or “voltage” relays are used with single-phase capacitor-start/capacitor-run motors, which need relatively high starting torque. Their main function is to assist in starting the motor. Knowing the sequence of operation for this type of starting relay can help you diagnose, confirm, or rule out certain service problems.
The big push is on to replace R-22 unitary air conditioners and heat pumps, and it looks like the industry has really and truly decided that R-410A systems are “it.” This article offers an overview of some of the issues related to R-22 and -410A in the field: operating pressure differences, oil characteristics, and temperature glide.
Bob Forty knows all about condensing coils. As president of Energy Services Air Conditioning and Heating Co., and a 30-year self-proclaimed student of the hvac industry, Forty has seen a lot of trends come and go. One of the trends he’s not happy about at all is condensing coils that are made from aluminum (aluminum tube/aluminum fin).
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