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 […]

Often in commercial HVAC and refrigeration, you'll come across a sight glass/moisture indicator on the liquid line. (Oil sight glasses also exist, but those are different from what I'm talking about today.) Sight Glass The sight glass portion is simple; it's just there to show if the liquid line has a full line of liquid […]

I once had an old commercial blower assembly on a 20-ton package unit, and the bearings and pulleys were seriously shot. I was 19 or 20, and as much as I tried, I just couldn't get the rusted hunk of metal apart. I tried penetrating oil, pullers, pry bars… I knew better than to beat […]