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 […]

This tech tip was written by a friend of HVAC School, Brian Mahoney. He is an HVAC instructor at Western Suffolk BOCES/Wilson Tech. Thanks, Brian! The podcast on delta T for A/C the other day got me thinking about the formula I learned in school about calculating the GPM of a hydronic system. We will […]

  Dehumidification features have been common on residential systems ever since the introduction of variable speed blower motors. The system is set up so that the blower can produce less CFM per ton when the latent load (humidity) in the space is higher than the setpoint relative humidity. Slowing the blower increases moisture removal by […]