David Holt

Why is it called single-phase 240 when there are two opposing phases (or legs)? I wondered why we called two 120v opposing legs “single-phase 240” for years. Then someone pointed out to me that a typical “single-phase” pole transformer only has one power leg entering and two coming out. That freaked me out. How can […]

Flowing nitrogen while brazing does not mean the air was cleared first. Learn how to purge large ACR piping, choose a practical regulator setup, and estimate time and cylinder use.

First off, the correct acronym for a GFI (ground fault interrupter) is “GFCI” (ground fault circuit interrupter). The purpose is to act as a safety device to protect from electrical shock. GFCIs are important components of electrical safety; they even make an appearance in our electrical safety video. GFCIs can be built into outlets, circuit […]

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 […]