David Holt

How does a typical single-phase motor know how fast to run? Typical induction motors depend on the electrical cycle rate of the incoming power (measured in hertz) for their speed. Our power in the US makes one complete rotation from positive electrical peak to positive peak 60 times per second, or 60hz (50hz, or 50 […]

Relays can be used for many different control applications, including controlling fans, blowers, other relays, 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 opens […]

We’ve all heard some version of the phrase “heat rises,” but is that really true? First, we need to remember that heat is energy, not matter. Heat is a force, not a thing. While heat may result in changes to matter (stuff), it isn’t matter itself. When we add heat to stuff, the molecules inside […]

David Holt with NCI returns to the podcast to discuss the evolution of HVAC training; we cover the past, present, and the possible future of training in the industry. In the past, we had a lot of hands-on training, whether it was one-on-one or in a traditional classroom setting. These learning practices remain beneficial today, […]

David Holt from NCI comes on the podcast to talk about airflow testing and its importance as a customer service tool for the HVAC trade. Charging and airflow are closely linked. Even though the charge may be correct, the system can’t operate correctly if the airflow is off. For example, we can only get the […]