Tech Info

General Rule for Cooling CFM Requirements:

 400 CFM Per Ton

Finding an Unknown CFM:

 (BTUH / (TEMP.Rise * 1.08))

Heating Output for Electric Resistance Heater:

(KW * 3413)

A rough but safe rule of thumb to use in the absence of available engineering data is to multiply the gross filter grille area in square inches by 2 CFM for each square inch. This will keep the face velocity below 400 FPM. For instance, if one thinks a 20 x 20 grille might be adequate, 20 x 20 = 400 gross square inches. Multiply this by 2 CFM per square inch and the result is a CFM of 800.