Thread: Calculating Cooling Capacity of AC Units

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Calculating Cooling Capacity of AC Units

This company im working for hasn't done an audit of their HVAC system in 20+ years. They have a bunch of Modine CSC-1515 units in their warehouse that were manufactured in the mid 60's.

I have little experience in the HVAC field, and few resources at my disposal (Manual N for Load Calcs). I have the Design Specs of the units from a previous audit, but would like to calculate the Cooling Capacity of each unit and am having difficulty calculating the BTUH / Tons refrigeration output.

Any help with equations or references to such is appreciated.

Thanks.

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CFM X Delta HT X 4.5 = total cooling btu

Return WB of 61.7= 27.62 btu's per lb of dry air (plotted on pycrometric chart)

Supply WB of 54.2= 22.74 btu's per lb of dry air (plotted on pycrometric chart)

Subtact the two and you get 4.88 that is you Delta HT

So lets say 1000 cfm X 4.88 X 4.5= 21,960 BTU

1000CFM X 4.88 = 4880 X 4.5 = 21,960 Total BTUs removed.

1000CFM X (16°Delta X 1.08) = 17,280 Sensible BTUs removed.

21,960 - 17280 = 4,680 BTUs Latent removed.

measuring indoor cfm for gas-oil heat

cfm= btuh output divided ( 1.08 x delta temp. )

measuring indoor cfm for electric heat

cfm= volts x amps x 3.414 divided ( 1.08 x delta temp. )

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best cfm measurement is a tesp measurement and match it to the blower performance chart

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