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The Problem with an Oversized Air Conditioning System

Here’s a piece of advice we cannot stress enough when it comes to residential air conditioning: you must leave the installation of a new air conditioner for a home to HVAC professionals. It is not only a matter of seeing that the new AC is correctly hooked up and will work as it should. It is also a matter of finding the right size of air conditioner.

“Size” in this case doesn’t mean the bulk of the AC. It is the cooling capacity (measure in BTU tons) of the system. An air conditioner must be matched to the cooling requirements of a home through a complex process called a heat load calculation. Simply guessing at how powerful an air conditioner a home should have will result in a system that is either undersized or oversized.

Why an oversized system is a major problem

It’s easy to grasp why an air conditioner that isn’t powerful enough to cool down a home will be an issue. No matter how long the AC’s compressor runs, it will not be able to send enough cooled air through the living spaces. But why would an air conditioner that’s too powerful be a problem? Isn’t the worst that would happen is that you would just end up paying too much to have it installed?

The truth is that an oversized AC will create as much trouble (perhaps more) than an undersized one. If the air conditioner puts out too much cooling, it will cause the temperature in the house to drop so rapidly that the thermostat will detect early that its setting has been reached. It will shut down the air conditioner’s compressor before completing the cooling cycle, only to turn it back on a short time later. This leads to a continuous start-stop process called short-cycling. Short-cycling will severely damage the compressor and shorten the air conditioner’s lifespan. It will also put a massive drain on your cooling bills. And on top of all that, shutting down the cooling cycle early means there isn’t enough time to evenly distribute the conditioned air throughout the house.

To avoid an oversized AC when you schedule air conditioning installation, call on the experienced professionals at Red Rock Mechanical. We serve Burlington, VT and the surroundings areas.

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