Electronic Portable Air Conditioner

Air Conditioning BTU Question?

I'm looking into buying a portable air conditioner unit. I'm curious to see as to how much it would cost me to run but I'm a little unsure how to get started. If I'm given the BTU's the air conditioner puts out, how can I use this to calculate a monthly cost for running it?

Public Comments

1. You need the AC power or AC current input. BTU/hr is related, but indirectly. A 12 BTU/hour unit uses typically about 11 amps at 120 VAC or about 1300 watts. Now you need to guess at what duty cycle it runs at. If it's really hot, it will run 100% of the time. If the room is small, it may only run for 20% of the time. You can tell by the sound when the compressor is running. When the compressor is off, it uses little power, just perhaps a 100 watts for the fan. So, get a wattage number from the unit, or it's documentation, or scale the numbers above. Now guess at the duty cycle. I'll use 50%. Now check your electric bill for your power cost per kW-hr, typically $0.10. So, example: 1300 watts x 50% = 650 watts If you use it 8 hours a day, 30 days a month: 650 watts x 8 hours/day x 30 days/mo = 156000 watt-hours/mo or 156 kW-hour/mo 156 kW-hour/mo x $0.10 per kW-hr = $16 per month .
2. First I would convert BTU/h ( I'm assuming the power of the unit to be measured like that) into kWh (I'm assuming that your electricity unit is the kilawatt hour). 1 BTU = 1.055 kJ, 1kWh = 1000 W*3600 ( There are 3600 seconds in an hour) Therefore, 1 BTU = 1.055 / 3600000 kWh If you're air conditioning unit is rated x BTU/h, then you would multiply the above by x to give you the number of kWh the appliance uses per hour and then multipy that by the number of hours it runs a month to get the total kWh used by it per month. Then you can simply multiply by the cost of a kWh which should be easily found on your electricity bill. This should be the maximum.