Roof top unit

[nizak]

Would anyone here know what the load of a 20 ton roof top A/C GFA unit would be 208/230V 3Ph? Even an approximation would be helpful.Thanks.

 

[LarryFine]

Approximation: 1kva per ton.

No nameplate specs?

 

[topgone]

Would anyone here know what the load of a 20 ton roof top A/C GFA unit would be 208/230V 3Ph? Even an approximation would be helpful.Thanks.

1 ton of refrigeration = 12,000 BTU (heat)
Power input = AC load(heat)/SEER (seasonal energy efficiency ratio)

Assume SEER = 10 BTU(heat)/watt(electric):

Power input = 20 x 12,000BTU/10 = 24,,000 watts

in kVA, assume: PF = 0.8; Pin = 24 kW/0.8

so Pin = 30 kVA

kVA/ton = 30/20 = 1.5 kVA per ton

With higher energy efficiency ratios (depending on the heat pump) and higher efficiency motors, you could use 1 kVA per ton as Larry said.

Still, it's best to refer to OEM datasheets.