What Size Air Conditioner Do You Need?

The capacity, or “size,” of your air conditioner affects its ability to meet your cooling needs. Does the size matter? After all, shouldn't a big unit do an adequate job of cooling your entire home? Well, no.

If an air conditioner is sized too big, it will cycle on and off often. This is called “short cycling.” A cycle is the term HVAC professionals use when they are describing how often all of the indoor air is fully conditioned per hour. If your central air conditioning cycles three to five times per hour, it conditions the air that many times. Three to five cycles per hour is ideal.

An AC that short-cycles may turn off and on twice that many times with a much shorter run time. Turning on and off quickly doesn’t allow the cold air to mix well with the hot. As a result, there will be warm and cool spots throughout the house.

And because the air doesn’t mix well, the HVAC system will leave behind excessive humidity. That will make it feel even warmer.

It’s also a waste of energy. When the AC has to turn on that many times, it will burn energy quicker than is optimal. And any machine that has to start often will wear out sooner than it should. Instead of getting a full 15-20 years out of your investment, it may last only 10 years.

Signs Your Air Conditioner May Be Short Cycling

If an air conditioner is too small, you get a different set of problems. On days when you don’t need 100% cooling, it will do fine. But on the hottest days of the year, it won’t keep you cool. It will run and run, driving up your energy bill without cooling you off.

Signs Your Air Conditioner May Be Undersized

What Is a Manual J Load Calculation?

There are two common, incorrect ways to figure out the size of an air conditioner. A salesperson might look at the old unit and recommend the same size. The problem with that is there’s no guarantee the existing unit was sized correctly. A new unit will have the same problems as the old one if the size is wrong again. This is also true if the house has been modified; the old unit may have been right when it was installed, but the needs of the house have changed since then.

The second wrong method is to take the home’s square footage and use no other calculations. This might come close, but it’s lazy and frequently incorrect.

To correctly size your air conditioner, your HVAC contractor must measure your home by doing a load calculation. A Manual J load calculation is a set of analyses determining how much heat your home gains and loses during a given season.

A load calculation looks at your home’s square footage and features that affect heat loss/gain. These factors include the number and size of windows and doors, the height of your ceilings, the type of basement you have, the number of occupants, and more.

Why Do Contractors Skip a Load Calculation?

What Is a SEER Rating, and Why Does It Matter?

Another consideration in purchasing an air conditioner is the SEER rating (Seasonal Energy Efficiency Ratio). This rating determines how efficient your system is. The higher the SEER, the more efficient the AC.

The majority of modern air conditioners have a SEER that ranges from 13 to 21. Starting in 2023, the minimum requirement increased to 14 SEER. And usually, as the SEER rating goes up, the price of the AC increases. However, because it will be running more efficiently, the operating costs will be lower at these higher SEER levels, which can reduce the long-term costs of your system.

Read more: What’s a Good SEER Rating and Why Is It Important?

Do I Need a High SEER Rating?

A higher SEER rating will mean that your air conditioner will run more efficiently, but there are other factors to consider. The SEER rating of your system can also decrease over time. We had seen older systems that were likely a SEER 10 or lower when installed but they had deteriorated to an even lower SEER rating by the time they were replaced.  If your system falls into this category, you will likely experience significant energy savings by changing to a new system.

Consider these factors when trying to determine the best type of air conditioner for your home:

A single-stage air conditioner is going to be the least-efficient option because it has to be at 100% on or completely off the entire time.

A more energy-efficient unit can help keep your bills low and is also better for the environment. A two-stage air conditioner is going to be a more energy-efficient option, with variable-speed air conditioners being the most efficient. Both options do not have to operate at 100% power and use smaller amounts of energy to function.

A high SEER rating is a good sign that you have a more energy-efficient system. If you are looking for a different efficiency marker, you can always look for the Energy Star rating symbol. Energy Star-certified products meet strict energy efficiency guidelines set by the U.S. Environmental Protection Agency (EPA). This means you can enjoy a comfortable home while saving energy.

Do You Have to Replace Your Furnace at the Same Time as Your AC?

The only way to ensure that your new air conditioner performs at its rated efficiency is to replace your heating system at the same time. It’s especially recommended if your furnace is more than 15 years old.

If you buy a new energy-efficient air conditioner but connect it to an older furnace and blower motor, your system will not perform to its rated efficiency. This is because the air conditioner relies on the furnace’s blower to distribute cold air.

If you have a variable-speed air conditioner that’s connected to a single-speed blower, the entire HVAC system turns into a single-speed unit. In some cases of mismatched equipment, the air conditioner won’t work at all. Check with your HVAC contractor if you have concerns.

Read more: Do I Need to Replace My AC and Furnace at the Same Time? Pros & Cons

• Checking the filter and replacing it if necessary. The majority of air conditioning problems are associated with a clogged furnace filter.
• Checking airflow from the blower fan
• Checking pressure levels against manufacturer standards, which are ideally the same baseline pressures that were measured at the time of installation. Various pressures might need to be inspected, such as gas pressure, refrigerant pressure, exhaust pressure, static pressure, and air pressure.
• The basic operation of the system, inspecting for noises or air leaks.
• Checking the refrigerant to see if there are any leaks. Minor leaks might only require a refrigerant “top-off.” Others are severe enough that your refrigerant line will be empty after weeks or even days.

New Air Conditioner Installation and Replacement in Gahanna, OH

Buying a large, expensive appliance, let alone one that cools your entire home, is never easy. So if you live in Gahanna, Ohio, or the Central Ohio area, please give us a call to start that process today.

At Fire & Ice, we take pride in doing the work correctly the first time. Whether it’s a repair, a replacement, a new installation, or a tune-up, we have the expertise and knowledge to get your system working to provide the most comfort to your home.