Have you ever looked at the thermostat for your house and seen the lowest setting—which is usually 60°F—and wondered if the air conditioning system could make the house even cooler than that? True, you wouldn’t want it to be colder than 60°F, which is already too cold for most people, but what are the actual limits of an AC?
This isn’t a frivolous question. Even if you don’t want to turn your home into an icebox during the summer, understanding the boundaries of what your air conditioner can do will help you know how best to set the thermostat and how to avoid pushing your AC harder than its limits. We’re going to examine those limits below.
The 20°F Temperature Differential
The simple answer to “how cool can an AC make a house?” is “20°F cooler than the outside temperature.” This is what is known as the temperature differential for the air conditioning system. A central AC for a house can, at most, remove enough heat from a house to lower the indoor temperature by 20° compared to the outside. This is usually more than enough to deliver comfort to a house, provided the air conditioning system was properly sized when it was installed. (If amateurs did the installation and undersized the AC, it won’t be able to reach a comfortable temperature no matter how the thermostat is set.)
Let’s use an example of our local summer temperatures. Our hottest months are July and August when the average high during the day is 84°F. On an 84°F day, your air conditioning system could lower the indoor temperature to 64°F—which is far cooler than you need. We recommend a setting of 78°F to help conserve energy, and in 84°F weather, that’s no problem at all for a correctly sized AC. You’ll still be able to maintain that temperature even when the weather gets to 98°F.
On the rare occasion our summer temperatures rise to 100°F, your AC may struggle to keep the house at 78°F. In these cases, nudge the thermostat up a bit. This will keep the AC from running continually and wasting energy.
When the AC Can’t Keep Up
Now that you know how cool your AC can make your house, you’ll have a better idea of when the air conditioner is malfunctioning. If you can’t get your house to a comfortable temperature during a standard hot summer day, there may be trouble with the air conditioner. We already mentioned an undersized air conditioner, but there are other problems that can result in a cooling system that can’t keep up with the heat: a clogged air filter, refrigerant leaks, short-cycling, dirty condenser or evaporator coils, or a system that is simply getting too old.
To find the answer to your AC’s cooling problems, call our West Chester, PA HVAC pros. We can find the solutions that will let your AC deliver on that 20° promise!
Michall Daimion Heating & Air Conditioning, Inc. has been the Main Line’s Premier Service Provider since 1976. Call us when you need great AC service.