If you don't do a lot of commercial work, you may see a system like the one above and wonder what the heck it is. It is a 100% fresh air unit or a makeup air unit. You will see them more and more as codes start to reflect that balanced ventilation and conditioned outdoor […]

Before the fighting starts about term definitions, let's just settle on using “adjustable drive pulley” and “sheave” interchangeably to describe the belt-driven power transmission device shown above. Second, for the newer tech, you shouldn't be altering these sheaves so that the belt rides lower or higher in them unless you know EXACTLY what you are […]

  What should the delta T (ΔT) be? What do you mean!? 20 degrees, of course! We are referring to the air temperature drop across an air handling unit or evaporator coil in cooling mode. Actually, depending on who you ask, the answer will range between 18-22 degrees Fahrenheit. Heck, I’ve heard some insist that […]