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The Problem with Improperly Sized Air Conditioners

outdoor-ac-unitImproperly sized air conditioners is a surprisingly common problem. Unfortunately, the problem is always due to the negligence of the HVAC technician who installed it, and you’re the one who has to pay for it. In this post, we’ll explain why it’s so important to make sure your HVAC contractor in Salt Lake City, UT takes all the proper considerations into sizing your unit.

Why Sizing is Necessary

Before the 1980s, the design philosophy behind air conditioners was simple: more power means quicker cooling. And who wouldn’t want quicker cooling? The problem, however, was that this approach threw efficiency out the window. The homeowner would be the one footing the bill for all that extra power.

As HVAC technology advanced, the focus shifted to finding the perfectly sized unit for each individual home. The right sized unit, combined with long cooling cycles, would allow the home to be cooled sufficiently and without exerting unnecessary amounts of energy. And that means the homeowner would now be looking at a much more reasonable energy bill.

This meant that before installation, the HVAC technician would now have to determine the best-sized unit for the home using load calculations, which included factors like total square feet, climate, number of windows in the home, and more—anything that could possibly affect how well the home receives cooling power.

The problem is that not every HVAC contractor goes through the trouble of making these load calculations. Worse, an inexperienced technician or salesman might estimate the size needed by referring to a guide or handbook. When that happens, you’re bound to get an improperly sized unit.

AC is Too Small

If the AC is too small, the result isn’t all that unexpected: it won’t have enough power to cool your home properly.

What you’ll get, then, is an AC that has to run for extended periods of time, never quite able to reach the temperature shown on your thermostat. There’s also a possibility that rooms on the farthest end of the house won’t receive the cooled air, resulting in what would feel like “hot spots.”

You can also put your hand up against the air vents to see if there’s low air flow. That, combined with continuous running, could indicate an undersized unit.

AC is Too Big

Surprisingly, an AC that’s too big won’t act opposite of how an undersized unit would; it won’t make the home too cold. Instead, the unit will turn on and off very rapidly, failing to hold the temperature set on the thermostat—a process known as short-cycling.

When the AC is correctly sized, it will cool the air through numerous cooling cycles. These gradually fill the home with cold air until the home is able to hold that new temperature for a length of time. As the cool air begins to dissipate and the temperature raises again, another cooling cycle will begin.

With short-cycling, the AC will lower the home’s temperature too quickly, thus triggering it to turn off and then back on again. Another problem with short-cycling is that the AC’s start-up and shut-down cycles require much more power than continuous running. Not only will this wasted energy make an appearance on your energy bill, but it will contribute to excess wear-and-tear on the machine.

Need help with a badly sized unit? Contact At Your Service Plumbing, Heating & Air today!

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