HVAC specialist Derek Cole explains that air-conditioning systems run most efficiently during longer, continuous periods rather than short cycles. An oversized unit short-cycles and wastes energy, while a correctly sized system naturally runs longer, which is actually what you want. Think of it like highway driving versus stop-and-go traffic.
Questions this video answers
Longer continuous run times are more energy efficient, provided the system is properly sized and the thermostat setpoint is appropriate.
Is it more energy efficient for the air conditioner to come on for short bursts of cooling or to come on and stay on for long periods?
Yeah, great question. So you got to think about it kind of like miles per gallon. So think of your air conditioner as your car. Is it more efficient when you drive for you to be in traffic, stop and go, or is it more efficient for you to be on the interstate and You're gone. Which one's better? The interstate, right? So if the system is sized properly and is designed properly, it will run for longer periods than if it was too big of a unit, it would turn off quickly. If it was too small of a unit, it would run all of the time. I had a customer come in here a couple years ago and she said, "My AC won't stop running. It's like 95 degrees outside." I said, well, what's your set point inside? She said, um, like 75. Like, what's the temperature? 75. I say, well, that's good, right? She said, no, it won't stop running. I said, well, it doesn't want to get behind the temperature. So kind of when you think about it, so when you drove up here from your house, how many times did you turn the air off in your car? She said, I didn't. I said, why not? She said, because it would have got hot. I said, exactly. Same way in your home. So on those really hot days, it's going to run and run and run because it doesn't want to get behind. Um, so if you got it set on 75 and it gets to 75.2, it's going to turn on. Uh, now they don't show you the point and the dots between the numbers because that kind of freaks you out, because it'd be like 75.6, you're like looking all the time like, 75.6, oh my goodness, it's getting hot. So they, they only go with the round number, 75, 76. So the system should be sized properly, and if it's working properly, it is going to run. You want longer run times because it would be more efficient to run longer. So hope that makes sense. I think that answered the question. The answer pretty good.
Yes, very good.
Awesome.
Should I leave interior doors open or closed during heating and cooling?
You go into some houses and the door's shut and you open the door and it's like 65 degrees in that room. You're like, "Oh, feels good." So it depends on the house. Now the ideal situation would be to have all the doors open all the time. Some houses, when you shut the door, it is right to the carpet. So it is trapping the air in there and it's not coming back to the unit, which is a problem. Some houses or mobile homes really have an undercut door where they got 2 or 3 inches there where you can shut the door and the air is just going to keep flowing out of that room. So that's good too. Now again, the ideal situation, keep them all open because whatever goes out needs to come back. So you don't want to restrict that airflow coming back in any kind of way possible. So if the air is blown out, you want it to get back to the return. Again, air is like water. Whatever is easier is the way it's going to go. So if it's hard for it to come back to the unit because your door is shut, it's going to pull air from the crawl space, from the attic. It's going to get the air back to the unit. So you want to make it conditioned, filtered, clean air coming back to it. Versus the air from outside, which you can't control. So keep the doors open when possible and watch for the door undercut because some folks I've been to the house and the door and the carpet is so thick when you shut the door you kind of have to pull it and it's really tight. That air is not coming back very easily. And then some houses you shut the door and they got like 4 inches under it and you're like, oh my goodness. That's plenty of room. So leave it open when possible. If you need to shut it, just be conscious of what needs to happen. In my personal house, I have to leave my door cracked a little bit because my carpet kind of comes right up to it. So if I want to shut my door, I kind of shut it with a gap in it. That way the air gets back to it because the unit really freaks out when it has no airflow.
