Let's take a deeper dive into the magic that is gas defrost. Most techs who are familiar with heat pumps understand the basics of a gas defrost. When we apply this strategy to a larger system where we're only reversing a small part of the system, we need to add some controls and valves to […]

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 […]

Every gas furnace data plate/tag has a specification for the temperature rise through that furnace. It is shown in a range, like 50-80° or 45-75°. Those two numbers are the lowest recommended temperature rise, and the highest allowed temperature rise through the furnace is usually a 30° difference. When possible, we want to get the rise […]