How to Calculate GPM for a VAV system?

[ColonialEngineer]

Forum Members,

Does anyone know how I might compute the GPM (gallons per minute) of heated water traveling through the coils of a heat exchanger, in order to heat up some air from 60deg to 85 deg at 450 CFM. The air is traveling normal to the heat exchanger and as it passes over the coils it is heated up. The cross section of the heatexchanger is small at 2 sq. ft. Any equations would help. I'll send you more detail if needed.

 

[quark]

Sensible heat, air side Q = 1.09 x cfm x dT
Sensible heat, water side Q = 500 x USgpm x dT

Equate the two and you will get flow rate of water. Surface area of the coil is OK.