A/C replacement for a load out room

[newfie401]

Currently trying to do an approximate estimate of the tonnage needed to cool a smaller room containing several transformers.
Theres nine trans. ranging from 30 kva to 1250kva. This is the first time looking into it and i've yet to find a way to calculate the heat in watts.

The previous system was a 10 tonne system, but using an approximation from engineering toolbox, the system would be giving off about 33 tonnes.

EX: 1250kva * 20 = 25000 watts of heat...

Anyone point me to some reading where I can varify the approximation or any help at all!

 

[ElSid1]

1) Ask the manufacturer of the transformer is always best.
2) Look up some tables in ASHRAE or other reputable publication to get an approximate value

 

[cdxx139]

I multiply transformer kVA by inefficiency (3-5%), thats the load in the space, then multiply by 3.4 to convert to Btu.

Thats your SENSIBLE load to meet.

1250 kVA * .03 * 3.4 = 127 MBH = 10 tons of cooling

knowledge is power

 

[cdxx139]

maybe they used diversity?

knowledge is power

 

[KiwiMace]

I have used 2% of projected load (and perhaps some margin) as the loss for a lot of transformers, but the inefficiency must come from the manufacturer. If you use the nameplate capacity you quickly get monster oversize. Electrical engineers do not size transformers near the duty point like you do with chillers.