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Serving Maryland, Virginia, and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun Counties and the
surrounding area

Monday - Friday 7:30am - 5:30pm | Saturday 8:00am - 1:00pm. CALL FOR EMERGENCIES


Serving Maryland, Virginia,
and Washington, D.C.

Serving Maryland and Washington, D.C.

Serving Fairfax and Loudoun
Counties and the surrounding area

24 Hour Emergency Services, 7 Days a Week

Home of Mr. Heat Pump

B&B Air Conditioning & Heating Service Blog

How Cool Can an AC Make My House?


You know your air conditioning system has limits. It can’t make your house as cold as the inside of the freezer in your refrigerator, after all. But when you look at the thermostat for your home, you might wonder if the AC could potentially go lower than the lowest setting on the thermostat. Most thermostats have a temperature setting low of 60–63°F, which is colder than most people want their homes to be. But theoretically, how cool can your central air conditioner make your home?

This is much more than a theoretical question! Understanding the limits on your AC’s cooling can help you know why air conditioning system sizing is so important and how air conditioners operate.

An AC’s Capacity vs. Its Temperature Differential

To explain your AC’s cooling limitations, we have to make a distinction between two different traits: the AC’s capacity and its temperature differential

When you’re shopping for a new air conditioning system, capacity is what you’ll pay the most attention to. Capacity is the amount of heat an AC can remove from the air over an hour, and it’s measured in both BTUs (British Thermal Units) and tons (1 ton = 12,000 BTUs). This isn’t a measure of how cool an AC can make the air, however. It’s a measure of how much cooling an AC can provide for the space it’s installed for. It’s best to have professionals handle purchasing a new air conditioner for your home since the capacity must match the house’s cooling requirements—neither too big nor too small.

Temperature differential, unlike capacity, is identical with all residential air conditioners. Rather than the amount of cooling an AC can deliver to a space, temperature differential measures how much the AC can lower the temperature of the air. This is standard at 20°F. So if the air in a house that enters the air conditioner through the return air ducts is 80°F, the AC can lower it, at most, to 60°F.

To give you an idea of how these two measurements work, a 3-ton air conditioner and an 8-ton air conditioner will both lower the temperature of the air they take in by a maximum of 20°F. That’s how much they can cool the air. But the 3-ton AC won’t provide the same volume of cooled air as the 8-ton one. If a house needs an 8-ton AC for comfort, the 3-ton system won’t do the job, even though it will still lower the air it does condition by a maximum of 20°F.

If your air conditioner was professionally installed, it shouldn’t have trouble cooling your house on most days. When your AC does start to struggle, it’s often a warning you need to have the system inspected and repaired. If your air conditioner is too small to provide enough cooling for your home, then you’ll need to look into a new AC installation in Fairfax, VA. Call us about this—we’ll make sure you have the right air conditioner to ensure your household enjoys the comfort it deserves.

Call on B&B Air Conditioning & Heating Service. We are always there when you need us.

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