Is it cheaper to run central air conditioning all the time, or turn it on and off?

Question

I have heard that setting the thermostat at a specific temperature (about 78 degrees) and setting it to automatically stop blowing cold air when it reaches that temp is cheaper then turning it on and off all summer long. I've heard that starting the air conditioner takes more energy then letting it run steady. We only want the upstairs bedrooms cooled down at night and we are trying to figure out the cheapest way. Thank you.

Answer 1

Yes it is true. We have one and have it set to 78 or 76. We do turn it on and off, but it's not really being energy savy. When you turn it off the temp in your house goes up yet again in most cases hotter than it is outside. Then you turn the ac on which would normal kick back on in your case at 79 or 80 degrees. Then it would only need to cool down 2 degrees. But when you turn it off and the temp in your house goes up to 86, and you want to bring it down 10 degrees, your starting the cooling all over. Hope that helped you out!

Answer 2

Yes, when you are away you should adjust the thermostat a couple of degrees but still leave it on, unless you are away for an extended period of time like days.....I leave mine set at 80 when home and change it to 82 or 83 when away for a few hours. It does not take long to cool back down to 80 unless I turn it off and come home to find it at 87 and then it takes hours to cool back down.

Answer 3

Depends on how well you house is insulated. Best way to tell is take a reading at your electric meter then run tour a/c for 24 hours and take another reading, minus the first meter reading from the second and that will tell you how much electric you used. Then just run it when you need it repeat the process of the meter readings and which ever number is smaller that's the cheapest way to run it. There are so many variables with houses and a/c efficiencies that there is no straight forward answer. Hope this helps

Answer 4

Im a air conditioning technician, your best bet is to buy a themistat with a timer on it so you can custom adjust the times of days,and seasons you want your system to run on.

It is less expensive to turn it off when not in use. 78 deg is the typical text book answer when programming your thermistat.

Id keep your upstairs thermistat set around 87, find a mid point for your upstairs unit. Yes it can use more energy if your system hasnt ran for a long time and it is tring to remove all that heat. (Remember this,Airconditioning is the process of removing heat) If your system is set to around 87, it will not run as long and have to remove so much more heat, also it will not turn on and off which can also be more expensive because your motors take more energy to turn them on than to run them constant. Your motors need more amps to start then run. (look up term locked rotor amps)

other ways to save energy is to always always change out airfilter every month, the dirtier it is the more resistance it creates which creates more amps, the less amps your motor runs on the less energy it will take to run them.