You can calc cooling capacity either using the water or air side flow and temperatures. Water is method is the simplest:
GPM*500*H20 Delta T = BTU/H Note: The 500 constant assumes straight water (no glycol)
For air you'll need to measure airflow and take wet bulb and dry bulb temperature readings across the coil. Find the resulting entering and leaving enthalpy for each using the psychometric calculator located here http://www.trane.com/commercial/soft...eb_toolbox.asp
CFM*4.45*Delta enthalphy = BTU/h
There you have it....Git 'er dun!
Never let weakness convince you that you lack strength.
The design gpm is usually documented on the equipment data page of the job drawing or you'll have to go back to the coil manufacture. If you figure out the specific gravity of your glycol mixture, there is another formula to correct the difference between water and glycol, using the previously listed formula. (Hope that makes sense) I can try and find that correction factor formula tomorrow, but the water formula gets you pretty close, even with a 33% prop. glycol mixture.