# Calculating Power

Hi: I have recently purchased a portable 110VAC Air Conditioner. The plate on the unit says 11.9 Amps, also says 14000 BTU/h. I have it plugged into a 20 amp breaker receptacle. I calculated the Wattage (110 x 11.9 = 1309 Watts) . 14000 BTU = 4103 Watts (14000BTU divided by 3.412 BTU/watt). I then divided 4103 Watts by 110 VAC = 37.3 Amps…Why doesn’t it pop the 20 Amp breaker? Nothing seems to match.

2 Likes

You have mixed your units. If you divide BTU/h by BTU/Watt you don’t get Watts.

2 Likes

I see. With the information that I provided, would 110VAC x 11.9 Amps be close enough to the actual power consumed by the unit?

1 Like

The simple answer is Yes, power in Watts is Volts times Amps. The complicated answer requires a power factor correction calculation. If you see references to ‘actual’ power it is probably working power.

2 Likes

Hi Jim,

BTU also isn’t a great measurement for an air conditioner, rather than generating heat like a resistive heater it moves heat using the heat pump.

The electrical rating will be for the heat pump and will be significantly less than the overall BTU rating (if you pick the reference frame in a particular way an air-conditioner can be over 100% efficient!)

1 Like

Thanks Jeff and Liam. You guys are smart.