How to estimate the capacity of a chilled water AHU designed for office comfort

I have a very old model AHU manufactured by YORK Borg Warner. The name plate of the AHU is missing too.

Is there a general rule of thumb to estimate the cooling capacity by the surface area of the chilled water coil?

Or by blower motor horsepower etc?

Thank you for any input.

If it is working you can find the duty from the flow rate and the delta t

Q = m x Cp x p x DT

Can't give you Rep Marc...must spread it around etc lol..

Thanks anyway Frank:)

Quote:

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Originally Posted by frank

If it is working you can find the duty from the flow rate and the delta t

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Chilled water flow rate or Air flow? Delta T of air or water? Tq

Airflow (volume) over the coil, air on temps, air off temps.

Delta T DB will give sensible heat capacity, Delta h will give total heat, probably the water test would be easier
Q= water flow rate x DT x 4.2kj/Kg ' C

for example:

Air quantity =370CFM
Temperature of air entering the coil DB = 78F
" WB = 67F
Temperature of air leaving the coil DB = 59F
" WB = 57F
Enthalpy of air at 67F WB = 31.62 BTU/lb
Enthalpy of air at 57F WB = 24.48 BTU/lb
enthalpy deference = 7.14BTU/lb
capacity = 4.5*370*7.14= 11888 BTU/lb