By far the most common question we get from customers is how much does it cost to run central air conditioning?
The formula for calculating the exact cost can be fairly intimidating but the following Laymans rule of thumb will provide you a budgetary amount that will only be slightly higher or slightly lower once the bills start coming in.
Steps to determine central air conditioning running costs
Determine the Amperage of your unit. For a 13 SEER unit which is the most common in Edmonton – a 2 ton unit is typically 17 amps, a 3 ton unit 19 amps and a 4 ton unit 21 amps.
Calculate the wattage used by your unit. All Central Air Units are wired to run on 240 volts so to calculate your wattage multiply the amps by 240. Eg; for a two ton unit it would be 17 x 240 = 4080 watts
Electricity is billed by KWh, to determine the KWh for the size of your unit divide the wattage used by 1000. In this case 4080 / 1000 = 4.08 KWH.
Multiply your cost per KWH, approximately 12.7 cents in the Edmonton area by your KWH. In the case of this 2 ton unit 12.7 x 4.08 = 51.81 cents per hour would be your approximate cost of operation.
If your unit ran for 24 hours a day the cost to operate it would be $12.43 per day or 375.00 per month.
A properly sized air conditioner does not run 24 hours a day, not even in 40 degree heat without any drop in temperature at night. As a general rule and assuming you set your thermostat to Cool to 21 degrees Celsius you can determine how many hours your unit will run during the day by using the following factors:
Outside temperature Multiplier
40 degrees .8
36 degrees .4
32 degrees .3
26 degrees .25
24 degrees .20
Multiply your 24 hours cost per month by the above factors to determine your approximate monthly cost based on weather patterns in Edmonton. In this case, the two ton unit operating with average outdoor temperatures of 26 degrees would be $375.00 x .25 = $93.75 per month.
