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Serving the Greater New Braunfels, TX Area

Serving the Greater New Braunfels, TX Area


Pushing the Thermostat Way Down Doesn’t Work: Here’s Why


How do you like the inside of your house to feel during the hot Texas summers? Probably cool. Not too cold, but enough so you can relax and forget about the scorching heat outside your walls. How do you manage the indoor temperatures with your air conditioning system? With the thermostat. But trying to find the right cool temperature on the thermostat isn’t as simple as it may sound. Often, people push the thermostat setting to its lowest point (which is usually 60°F) hoping they can more rapidly beat the heat. 

However, that’s not how either the thermostat or the air conditioner works, as we’ll explain.

Your AC Has Cooling Limits

The central air conditioning system in your house doesn’t have limitless cooling ability. After all, you can’t lower the temperature down to freezing. What are the limits of an AC?

For most residential central air conditioners, the amount they can lower the indoor temperature compared to the outdoor temperature is 20°F. This is called the temperature differential. So even though your thermostat can turn all the way down to 60°F, it can only do that if the outdoor temperature is 80°F or lower. And even then we wouldn’t advise it, as 60°F is too cold for most people and it’s not necessary to push the air conditioner that far for only a mildly hot day. You don’t want to strain the cooling system so much that you’ll need AC repair in San Antonio, TX.

Knowing the temperature differential for your AC will help you understand where to set the thermostat on extremely hot days. When it’s 100°F outside, don’t set the thermostat lower than 80°F or the AC will be forced to run nonstop as it tries to push past its limits and can’t get there. The US Department of Energy recommends a daytime thermostat setting of 78°F when people are home. This saves energy and slows down the rate the house gains heat. This setting will work up to a 98°F day, good for most of the summer.

Reminder About How the Thermostat Works

Another fact to remember about setting the thermostat is that it doesn’t work like a throttle: if you lower it more, it doesn’t create a greater amount of cooling or provide cooling faster. What it does is establish the temperature for the AC to reach. This means that the lower you set it, the longer the air conditioning system will stay on. This may put the thermostat setting beyond the AC’s temperature differential, which will waste energy and still not get the house cool enough. 

Even if the thermostat setting is within the temperature differential, pushing it doesn’t lower won’t provide better comfort. It will only make the AC expend more energy to reach a temperature that your household would probably find too cold.

So keep the thermostat at 78°F during the day when people are home, then raise it by 8°–10° at night or when the house is empty. You’ll have a healthier AC, lower bills, and a comfortable house.

At Thayer Air Conditioning, your comfort is our #1 priority! Just call us when you need AC repair—we’re already on the way! 

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