
Appendix 1: Formulas
Following is a list of formulas and equations in the order that they appear in the book, with a description of each:
P = (GPM / Cv) squared
Pressure (in PSI), expressed as a function of flow and Cv (valve coefficient.
MAT = {(RAT x %RA) + (OAT x %OA)} / 100
Mixed Air Temperature, expressed as a function of return air temperature and percentage, and outside air temperature and percentage.
%OA = {(MAT – RAT) / (OAT – RAT)} x 100
Percentage of Outside Air, expressed as a function of mixed air, return air, and outside air temperatures.
BTUH = 1.08 x CFM x delta T
Airside Heat Transfer Equation
BTUH = 500 x GPM x delta T
Waterside Heat Transfer Equation
BTUH = KW x 3410
Conversion of kilowatts to BTUH
KW = BTUH / 3410
Conversion of BTUH to kilowatts
PSI = ft. hd. / 2.31
Conversion of “feet of head” to PSI
