Skip to Content

Olive Explains Your Ac’s Cooling Limits

Dog Wearing Sunglasses

Greetings everyone! I’ve gotten some questions about just how cool I can be! 

Okay, maybe it wasn’t phrased exactly that way. People want to know just how cool an air conditioning system can make their house. It’s a good question: air conditioners do have limits, the same way that your car can’t do 300 mph no matter how well-built it is. And although we dogs can get super-fast—did you know that Greyhounds can run as fast as 45 mph?—none of us are going to outpace a Bullet Train no matter how healthy we are. Not meant as a criticism! Just basic facts about how things work.

So, what’s your air conditioning system’s “top speed”? I’ll get into that below. Please hang around, this can be helpful with setting your thermostat during summer.

Your AC’s Temperature Differential

“Top speed” for an air conditioning system is its temperature differential. That’s my fancy HVAC canine-speak for how much your AC can lower the temperature of the air in your house compared to the temperature outside. 

If you go look at the thermostat for your house, you’ll notice that it can be set as low as 60°F. But that doesn’t mean your AC can always get the home that cold. (And 60°F is really too cold, no matter what.) This is where the temperature differential is important. Most residential air conditioning systems have a temperature differential of 20°F. (Or 11.1°C. I just wanted to show you I know how to do Celsius calculations.) So if it’s 80°F outside, you could lower the indoor temperature to 60°F. Again, I don’t recommend this, but it’s within the AC’s capabilities of 20°.

But if the temperature outside is a blistering 90°F, how cool could the AC make the house? Yep, easy math: 70°F. Trying to set the temperature on the thermostat lower than this is just going to force the AC to work and work and work nonstop as it tries to get to a household temperature it cannot actually reach. That’s wasteful and not good for the AC.

Practical Thermostat Settings 

The good news is that you don’t need your home cooled down to 70°F to stay comfortable. I’ve talked about this before, but the ideal energy-saving setting is 78°F during the day when people are home, raised by 8°–10°F at night or when the house is empty. With a setting of 78°F, your AC can handle outdoor temperatures up to 98°F—you’re good for most of the summer!

When the temperature rises over 100°F, that’s when to be cautious with your air conditioner and raise the thermostat setting a bit higher. You don’t want the AC to overwork during a heatwave, because that’s the fastest way to have it break down. Of course, you can call us when your air conditioning in Knoxville, TN needs heatwave rescue, but I know you’d rather just have it keep cooling away. And now that you know about temperature differential and your AC, you have a new tool to help your air conditioner stay in great shape!

Stay cool,