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 grounding and bonding process is important, and it's a fairly broad topic. In HVAC/R, we generally just need to make sure that we properly connect the conductors (wires) provided to the proper connection points in the equipment and occasionally the disconnects. These connection lugs or green screws are rated for grounding so long as […]

For those of you who use the MeasureQuick app for system diagnosis and performance testing, you may have noticed the “fan efficacy” results and wondered what it is. It is simply the CFM output of the system divided by the wattage used by the blower. It is only for the blower motor and has nothing […]