Is a Larger AC System Better?


Bigger is better. You’ve heard the term before, and you’ve probably applied it to multiple areas of your life. But does the saying hold true for your air conditioning system as well? Unless your home currently has an undersized AC that is struggling to meet the tonnage needed, you’re probably better off finding out exactly what size AC you need, rather than simply upgrading to the next largest size.

Overtonned Houses

Many years ago when central AC became more prevalent, most of the houses that it was installed in weren’t very energy efficient. They were drafty, often had poor insulation, and single pane windows. As a result, a larger air conditioner was needed to keep up and ensure the house stayed cool.

Times have changed, however, and houses continue to become much more energy efficient. People are sealing up air gaps, putting in energy efficient windows, and adding insulation to their homes. They’re also repairing old and faulty ductwork that could be losing energy as the air travels along it.

Because of this, air conditioners no longer need to be so large. (Installing an AC unit too large for a space is known as “overtonning”.)

While you may think that this isn’t a problem, it actually creates a situation where the air conditioner is only working at roughly 60% of its capacity, but using more energy and wearing out faster than an air conditioner that is correctly sized to the house. If your air conditioner is too large, you’re going to pay more for energy usage each month, more money in maintenance bills, and the AC is probably going to wear out faster and require replacement earlier than a smaller unit.

Finding the Right Sized Unit

You shouldn’t go out and purchase a new unit that matches the size of the old one, and you certainly don’t want to upgrade to the next largest size if you don’t feel the old one is working well enough. How do you find the right size?

By having your heat load calculated by a trained professional.

NATE certified professionals can measure your home, including the heights of your ceilings, and take into consideration things like how much sun your home gets, and how energy efficient it is. They can then give you the exact amount of tonnage your home requires to keep it cool – not too much or too little.

The end result is a home that stays comfortable, and doesn’t elevate your energy bills each month.

Getting the Most Out of Your Unit

If you think that you need to increase the size of your unit because it isn’t keeping your home cool enough, there are a few other things that you may want to consider first.

Air Gap

Poor air gap is responsible for the loss of as much as 30% of your home’s inside air. That means that 30% of the air that your air conditioner is cooling could be lost to the outdoors. If this is the case, getting a bigger unit won’t do anything but leave you with higher bills. Instead, seal up your home to make your current unit 30% more effective.

Leaky Ducts

Rusty, dirty, or leaky air ducts can result in a 20% loss of the air that leaves your air conditioner. This makes your air conditioner work harder, and keeps your home from getting as cool as you’d like. Making sure your ducts are regularly cleaned, and ensuring that they’re in good condition can help your current unit work more efficiently.

Dirty Air Filter

Your air filter helps keep particulates out of your air conditioner that could hinder the way it works. The filter needs to be changed every one to three months to ensure that air can continue to flow through it unimpeded.

If you haven’t changed your filter recently, dust, debris, and pet hair could be clogging it up, which makes your air conditioner work harder to pull air in. This lowers its efficiency and effectiveness —which could have you thinking you need a bigger unit, when you actually just need a new filter.

Schedule a Consultation

The best way to ensure that you have the right sized AC unit for your home is to schedule a consultation with a NATE-trained technician who can evaluate your home and let you know the best size for the job. You may be surprised to find that you need a smaller unit than you currently have to cool your home efficiently.

Precision Air & Plumbing August 30, 2017


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