How should I program my A/C to gain maximum efficiency?

Question

I have a two-story house and like most two-stories it's hotter upstairs where the bedrooms are. During the day I'm mostly downstairs and of course at night I sleep upstairs. My thermostat which is downstairs is set really high during the day (83) and 72 at night. During the day, the temperature's usually about 78 max downstairs where I spend most of my time so the A/C never turns on and I just deal with the natural temp. But then by about 10p, the A/C kicks in to bring the temp down to 72 (a process which sometimes takes a few hours). Am I wasting energy by causing this drop at night? Should I reprogram my thermostat so that the system is at a constant temp (say 72) all day long?

Answer 1

I am fascinated by the way people employ prose to describe a sensory process, particularly when apparently intellectualizing that process.
Would it not resolve the problem to find a timing and setting which maximises your own comfort?
Is that not the purpose of air-conditioning?

Answer 2

To gain maximum efficiency, the best thing you can do for your AC is "set it and forget it." Moving the dial around here and there thoughout the day can cause unnecessary starts and stops and thereby age your AC's compressor. And - as you noticed, its a lengthy process for the AC to try to move the house several degrees at a time. AC's are more efficient at maintaining a given temperature than cooling the place by 5 or so degrees.

So if 72 is your number, so be it. If you can stand 75, all the better for your electric bill.

Good Luck.

Answer 3

The short answer, yes. Set you thermostat to 75. Use ceiling fans to augment the ac. Have a attic extractor, or gable fan installed, this will dramatically get rid of the hot air trapped in the attic that normally would infiltrate your bedroom ceiling heating it up. If the attic is cooler, the house is cooler, the ac won't have to come on or run as long to pull down the house. I live in sunny Florida incidentally, and have worked as a ac tech.

Answer 4

It sounds like your afraid of having your AC turn on at all during the day. Instead of living in a multi climate house, keep the fan going on your unit during the day. It circulates the air more evenly throughout the house and is actually cheaper to run. It doesn't take a lot of energy to run the fan. I know its counter intuitive, but its true and it works.

For verification, call any reputable home inspector.

Answer 5

Have you local HVAC professional come over and talk to you about your system. I am in this business, and I know there are a few things that can be done to help you. Among them, you can have a second thermostat added for upstairs and thus your two floors can become separate conditioned areas. Make your central system do what you want, it is there for your comfort, why not use it for that.