Relays can be used for many different control applications, including controlling fans, blowers, other relays, or contactors, valves, dampers, pumps, and much more. A 90-340 is a very common, versatile relay that many techs have on their truck. So, we will use it as an example. A relay is just a remotely controlled switch that […]

The primary role of setting an appropriate level of subcooling is to ensure that we deliver a full line of liquid refrigerant to the metering device. We want to do this at: A pressure differential required by the metering device At a temperature and pressure no higher than required for maximum capacity and efficiency But […]

Note: My brother Nathan wrote this a few years back, and I only did some minor editing. A pool heat pump is essentially a water-cooled air conditioner in reverse. It usually has a large air evaporator on the outside that looks like a condenser coil and a heat exchanger (usually tube-in-tube) on the inside. A […]