Hello, Is it more cost effective to keep the air conditioner thermastat set at 79 all the time or to turn it up to 81 during the day while at work and then turning it back to 79 when you get home late afternoon? It seems to take a long time to bring the temp back to 79 and seem to use more energy. True or false??
Thanks, Sandy

I would keep it at 79.

Either way your going to pay for it, whether you let it cycle all day or run for a couple of hours at night it's going to be pretty close to the same cost. I would advise leaving it set at 79, this way it is half way comfortable when you get home.

Hello, Is it more cost effective to keep the air conditioner thermastat set at 79 all the time or to turn it up to 81 during the day while at work and then turning it back to 79 when you get home late afternoon? It seems to take a long time to bring the temp back to 79 and seem to use more energy. True or false???
Thanks, Sandy
For an 8 hour absence I would turn it down, not off. There is no such thing as free energy. Depending on how much the unit will need to recover if turned off will determine the cost.

I've tried this before. For me, leaving the tstat on a cooler temperature during the day, instead of changing it, costs a little less for me (I left mine at 76, in an apartment though). It may be different for you.

I believe that the laws of heat transfer would indicate that the greater the difference between the inside and outside temperature, the greater the amount of heat tranferred over a given period. That is why the utility companies state that for every degree higher that you set the thermostat, your electric bill may be 3%? Lower. If the setting is a bit higher during the 8 hours of the heat of the day, and lowered upon your return, you should save money.

It all depends on how long it runs. Having it cooler in the day and cycle more often may have it run less than if you have it warm in the day, and then try to cool it down in one shot. That one shot may take a longer time to cool down.