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 […]

We have discussed DTD (design temperature difference) quite a bit for air conditioning applications, but what about refrigeration? Let's start by defining our terms again. Suction Saturation Temperature The saturation temperature is the temperature at which the refrigerant will be at a given pressure if it is currently changing state. This change of state would […]

In HVAC/R, we are in the business of moving BTUs of heat, and we move BTUs via pounds of refrigerant. The more pounds we move, the more BTUs we move. In a single-stage HVAC/R compressor, the compression chamber maintains the same volume no matter the compression ratio. The thing that changes is the number of […]