ECN Forum Forums General Topics of the Trade General Discussion Area Compressor Amp Draw

Does anyone have a chart for rule of thumb amperage draws on HVAC and refrigeration compressor based on tonnage??

For instance how many amps does a 208v, 3ph, 5 ton compressor draw?

GJ

Obviously you are looking for a way to estimate site unseen for ball-parking a bid or having some idea for sizing something. Just thought I'd say that before you get "You really should size it off the nameplate rating".

I don't know off hand for your example, but I've found for single phase 240 volt, about 10 amps per ton. That's breaker size. 5 ton 50 amp breaker, etc.

Jps,
You are correct, I'm looking for a ballpark estimate. The final circuit sizing will be done from the nameplate info.

We are running to more and more requests where people are trying to save on the engineering. Tough to bid when it's all rather undefined.

I found a conversion that says 1 ton=4.71HP. Going back to my example then I calculate;

5 ton = 5 x 4.71 = 23.55hp

The amp draw for that doesn't come close to matching carrier's data for a 5 ton RTU. Carrier says that a 5 ton RTU 208v, 3ph, has a FLA of 32A.

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12,000 BTU (1 ton) = 4.7161 horsepower hour as a raw calcultion with formulas.

It does not translate into hp/ton on small equipment.