In the trade, we talk a lot about changes in enthalpy, especially when we are looking at total heat exchange over an evaporator. Sometimes, you will bump into the word entropy, and I wanted to take a stab at making it more understandable. Many people understand entropy as the condition in which molecules become more […]

To answer the question in the title, we use it as a measurement of pressure. REALLY, it is a measurement of distance. First, any scale CAN be used to measure vacuum (negative pressure) and positive pressure. The trick is knowing which is best suited for which and the size of the scale. Larger units of […]

This article is written by one of the smartest guys I know online, Neil Comparetto. Thanks, Neil! Recently, I posted a question in the HVAC School Group on Facebook that went like this: “When designing a residential duct system, what friction rate do you use?” As of writing this, only one answer was correct according […]