How Big Should My Air Conditioner Be?

At least once in life, every patriotic American should take a long look in the mirror and ask themselves, "How big should my air conditioner be?"

Most homes heating and cooling needs are satisfied by a properly sized HVAC unit. However, there are times and circumstances in which some homes have either too much or too little air conditioning power. Neither is an ideal scenario. So while it is important to ask, "How big should my air conditioner be?" you really ought to also ask, "How much do I actually need?"

Seriously, How Big Should My Air Conditioner Be?

Determining the right size air conditioner isn’t always just based on square footage, but on many factors which are specific to your home. These factors may include:

  • how many trees and shrubs are able to cast cooling shadows on your home
  • how many windows are facing certain directions in your home
  • the age of your home
  • how well your home is insulated
Factors Specific to AC Needs

These are all things to consider when choosing the right size air conditioner for your home. More natural shade, fewer south-facing windows, and better insulation means you likely need a smaller capacity system. By contrast, an older home with poor insulation and large windows facing south may require more power.

And don’t forget seasonal temperatures! Homes in places where there is a hot climate versus homes in moderate temperatures have different needs. The home in Minnesota would require a smaller unit compared to the exact same build in Texas.

Air Conditioner Capacity

Air conditioners are typically sold by tonnage. The smallest is usually a 1-ton unit. The largest AC Capacity Differencesresidential HVAC system typically available are 5-ton units (please note: this is the cooling capacity not the weight of the unit.) If you have a house that needs more than 5 tons to cool it effectively, you're out of luck.

I'm kidding! Instead of a single 5-ton unit, you’ll want to investigate installing 2 smaller units that have a cooling capacity combined larger than 5 tons. This will often make temperatures in your home more even.

Why would that be the case?

Multi-Level Homes

The most common scenario in which sizing can get wonky is when your home is multi-level. Bedrooms on the top floor can be difficult to cool correctly, without freezing out the basement and everyone in it. It’s also hard on your utility bills as you waste energy unnecessarily with over-cooling the bottom floors, it’s similar to leaving your lights on in rooms that you’re not using.

In this case, it can makes sense to break down what you need by floor. You will likely get better performance with two different units with 2 different thermostats, one upstairs and one downstairs. So if your entire home needs 5-tons of capacity, you might really be better served by a 2-ton upstairs and a 3-ton downstairs (or however it breaks down for you).

Another scenario to justify having two HVAC units is for large homes. If your home is single-level and over 3,000 square feet, it’s probably a good choice to have more than one unit. If you have more square footage than your system can effectively heat or cool, it will put unnecessary wear and tear on the unit which shortens its lifetime and costs more in utility bills in the long run. Long, single-story houses, like ramblers, are especially prone to uneven heating and cooling and the distance of the ductwork can reduce the power in which the blower motors can push the air.

AC for Multi-Level Homes

Zoned Air Conditioner Systems

Many homeowners have closed the vents in the basement and the main floor, hoping for a more even cooling situation in the summer. This practice doesn't really work. What those folks really wanted is a zoned system.

A zoned system is a great way to condition different interior areas in different ways. If the kids are gone to college and no one is upstairs, you can turn down the comfort there. Don't use your back office very much? Then don't cool it like you do your bedroom or family room. Zoning works best when it is built into the home from the beginning. A retrofit is possible, but can be expensive.

How Big Should My Air Conditioner Be is Only the Beginning!

Hopefully we have demonstrated that bigger isn't better. You can have an air conditioner 'big' enough for your home, but it still might struggle to provide the comfort you want due to design or varying needs. Of course, too little is just as bad as too big. You don't want a unit that is working constantly just to keep the edge off.

Plus, it's always good to have a backup in case of failure. Because of the increased stress, air conditioner system failure usually happens in the dead of summer. That can leave you and your family vulnerable to extreme heat and discomfort. If your home has two separate units for two separate zones, you will at least have a refuge to which you can flee. This can be especially important for those who are heat sensitive, like the elderly.

No matter your set up, it is important to remember regularly scheduled maintenance for optimum healing and cooling results. Changing the filters in your furnace every 1-3 months, help keep debris away from your outdoor AC condenser unit and helps keep all the tubes clean and clear. This will save you money in the long run, prevent excessive maintenance and preserve the lifetime duration of your HVAC unit.

Questions  & Comments?

Do you have questions like "How big should my air conditioner be?", "Where can I get a great deal on heating and air?", or "Do I look fat in these pants?"

Just let us know in the comments!

7 comments (view/add)
  • James Johns
    James Johns
    Posted on 9/9/2020

    I am trying to figure out how many tons we need for a church 50 by 60 with 14 feet ceilings

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 9/10/2020

    That is a fairly big space especially with the high ceilings. Give us a call at 270-575-9595 and we will help as best we can.

  • Luciano
    Posted on 9/2/2020

    Hi there

    I'm "dating" your website and Mr. Cool split systems for about 6 months... but I couldn't figure out what size I need yet for the first part of the project.

    I live in Boston MA, in a 1800's house. My kitchen is 15x22 and have a cathedral ceiling of 13' on the peak. skylights, windows and patio door all over. Well insulated when remodeled 10y ago. Kitchen is heated with forced air with 2 registers which do their job well.No AC. Right next to it I have a family/living room of 15x 25 with cathedral ceiling of 9' on the peak with lots of windows but no insulation whatsoever where we cook in the summer and freeze in the winter (with only 1 baseboard heater and no forced air). Has a window AC of 15K BTU where freezes in on side of the room and is comfortable on the other side. Planning to remodel and add insulation next year.
    I was thinking of a 30K BTU 21.5 SEER Mr.Cool dual zone (12K for family room and 18K for kitchen). Does that sounds right or too little? With the split on a different wall I think it will be comfortable for the entire room.

    Please let me know so I can place the order and get over with....


  • Kyle
    Kyle from Ingrams
    Posted on 9/2/2020

    My main recommendation would be to have an engineering firm conduct a Manual J heat loss/heat gain calculation. That will tell you exactly the BTUs you need for heating and cooling. That said, it would be our guess that you probably need around 36k BTUs, at least until you can get better insulation. If you're planning to do that soon, you should probably hold off on putting in new equipment until that is done, then have a Manual J done. In terms of placement, that's tough. Ideally, you don't want to place a mini-split air handler in a kitchen or bathroom due to the excess humidity. It would be much preferable to have the unit blowing into the kitchen rather than actually be 'in' the kitchen.

  • Jonathan Stuart
    Jonathan Stuart
    Posted on 7/17/2020

    How big should the air conditioner be? Answer: It depends....haha!

  • Dino Canale
    Dino Canale
    Posted on 7/6/2020

    Hi I bought a 3.5 ton Goodman heat pump from you a year or so ago for a 1300 sq ft house we remodeled . In the attic is where the air handler is located . The system cools great but I am having excessive condensation problems an I am reaching out to you for some advise into this and I would appreciate any help.
    Thanks. Dino Canale

  • Kyle
    Kyle from Ingrams
    Posted on 7/7/2020

    With condensation problems, the first thing to check is the drain pan and condensate drain line. Is the pan clogged? Is the line clogged? Usually, there is a clog somewhere. If the problem isn't a clog, give our Tech Department a call at 270-575-9595 x300.

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