An air conditioner that’s too large or small will not cool your home well. Not only that, but it will also use a lot more electricity and cost you more money in repairs than one that’s sized right.
If you have AC size woes and wonder if you have the size AC unit you need, you’re in luck! Today, we explain 4 signs your air conditioner is sized wrong!
You don’t have to be a math whiz to figure out if your AC size is wrong. A few simple observations can help you to determine if your air conditioning is running efficiently. And if at any time you have questions or want more help, our professionals are always available to assist you. Are you wondering: “What size AC unit do I need?” Call us today or stop by the largest air conditioning showroom in Tampa Bay, Florida for personal assistance you can trust!
Why Is It Important To Find The Right Size AC?
When it comes to air conditioners (AC), size matters. Bigger isn’t always better. A unit that’s too small can leave your home with hot spots. One that’s too big can make your home feel damp and uncomfortable.
The Department of Energy (DOE) reports that an improperly sized AC results in:
- Inadequate cooling
- Greater energy consumption
- Higher electricity bills
- System wear and tear
Specifically, a unit that’s too small for your home requires more cooling power. This leads to higher costs and difficulty reaching the desired temperature.
Similarly, an AC that’s too large will cool the room down faster, and then turn off. However, it has little time to remove moisture from the air. This leads to more humidity. In addition, an oversized system may lead to mold growth and poor indoor air quality.
Therefore, bigger isn’t always better. Instead, you can use several methods to determine what size system is best for your home.
4 Signs Your AC Size Is Wrong
Sign #1: My AC Doesn’t Run for Very Long
Do you notice that your air conditioner runs for short bursts? It never seems to stay on for long. You may think it’s fantastic how quickly it pumps cold air into your house, but this is a sign that your AC is too large.
Roaring at high power and shutting off again quickly puts more strain on your cooling system than if it were to run at a lower strength for longer. You may also feel sticky. This is because your extra-large AC lowers the temperature before it can get the chance to run enough to cycle through all of the air in your home.
This is called short cycling. It cools the air quickly, then shuts off. The problem is it doesn’t run long enough to remove humidity. As a result, your home’s humidity levels will rise. This makes you feel uncomfortable and puts extra stress on your system. Then, your system will require more repairs and have a shorter lifespan.
Sign #2: My AC Is Always Running
On the opposite side of the spectrum, if your air conditioning is always running, this is bad too. This can freeze up your evaporator coils! Your unit needs a healthy balance between how much energy it uses and how effective it is at regulating the temperature and humidity in your home.
If your AC runs all day, but your home feels warm, your system may be too small. A smaller unit cannot effectively cool your home, especially in hot climates. It works harder and uses more energy without providing the desired comfort.
When your AC is always running, it does a terrible job at saving energy and increases the cost of your electric bill. It also wears down the unit faster and causes more repairs.
Sign #3: Some Rooms Are Hot
You just installed a new AC or moved into a new home and you’re uncomfortable! Some rooms feel cool, while others feel hot. This could be another sign your AC is improperly sized.
When the AC kicks on, some rooms instantly become chilled, but not all of them. Other areas of your house continue to feel hot and muggy. What’s going on?
An oversized unit may cool rooms near the vents quickly but fail to reach rooms farther away. Then, a small unit that’s too small might not push enough air through the whole house. Either way, you are either reaching for a sweater or ripping it off.
When an AC is oversized, it won’t stay on for very long. Once the location of your thermostat reaches the temperature you set it to, the system shuts off. This usually causes many rooms to miss out on the air circulation they need to cool down.
Sign #4: My House is Always Humid
If your AC isn’t doing a good job at dehumidifying your home, it could be sized wrong. When an air conditioning unit is too big for the size of the space it’s cooling, it lowers the temperature so quickly that it can’t cycle through all your indoor air. If humid air isn’t pulled through the machine, it can’t function as a dehumidifier. If the unit is too small, it will struggle to do anything and make you miserable.
When your AC is sized correctly, it can pull every bit of air in your house through the intake vents and past the evaporator coils, drawing moisture out. Your house will feel cooler even at a higher temperature because the indoor relative humidity level will be perfectly positioned between 40% and 60%.
This is why energy efficiency is highly sought after. It not only helps your energy cost but balances how well your AC functions in our humid Florida climate.
What Size AC Unit Do I Need?
A poorly sized air conditioner is expensive and can make your home uncomfortably hot and damp. If you’re suffering from any of the issues listed above, you may be wondering, “What size AC unit do I need?”
We can help you to determine the perfect size unit for your property. For consultation, troubleshooting, or a new AC unit, call your local air conditioning repair and installation professionals. Choose Action Air Conditioning for all of your heating and cooling system needs if you live in Hillsborough or Pinellas County!
How We Determine What Size AC You Need For Your Home
Several factors go into determining what AC size is best for your home. The best way to get the most accurate calculation is through a Manual J load calculation. This is the standard method professionals use for determining AC size. The DOE recommends this step before installing a new unit.
Our HVAC experts consider the following:
AC Efficiency Ratings
Before choosing an AC, it’s important to consider efficiency ratings. Evaluate the AC’s cooling efficiency rating, known as SEER2.
SEER2 (Seasonal Energy Efficiency Ratio)
SEER2 is the total heat removed from a conditioned space during the annual cooling season. These values represent the cooling output of a system divided by its overall power consumption.
While the minimum SEER2 rating is 14.3 in some regions, aiming for a rating above 16 is best. This can lead to significant energy savings.
Upgrading your old unit to a system with a SEER2 of 16 can reduce your energy consumption by about 35%. So, if you pay $100 a month, your bill will be $35 less.
So, a high SEER2-rated unit has better cooling efficiency, saving you energy and money.
Calculate Your Home’s Square Footage
You should measure your home’s square footage before buying an AC. First, multiply each room’s length by the width. Then, sum the totals together.
British Thermal Units
Once you have the total square footage, you can determine what cooling power you need. Experts measure an AC’s cooling capacity in British Thermal Units (BTUs).
One ton of air conditioning is equivalent to 12,000 BTUs. Your AC needs 20 BTUs to cool each square foot of living space as a baseline requirement. So, multiply the total square footage by 20 to see how many BTUs your unit must have to cool your home.
For instance, a 3,000-square-foot home requires 60,000 BTUs. That means you would need a 5-ton AC unit. You can find the BTUs and tonnage under its product description.
Determine Which Rooms Need Cooling
You should base your calculations on how many rooms need cooling. If you want to include air conditioning in 3 out of 5 rooms, only measure those spaces.
Additional Factors We Consider When Sizing Your AC
Here are some other factors to take into account when choosing AC size:
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Ceiling height
Since AC size calculations usually assume 9-foot ceilings, add 1 or 2 extra BTUs for taller rooms.
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Sun exposure & windows
Homes with no shade or that face the sun will absorb more heat, causing more strain on your AC. Windows will also create additional heat in your indoor space. So, select a system with a higher SEER2 value.
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Number of people in the home
The number of people in your home affects the size of the AC unit you need. Add 100 BTUs for each person in your home to the total BTU calculation. People create a lot of heat, adding to the house’s cooling load.
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Insulation quality
Poorly insulated homes have more air that escapes, increasing the load on your AC. When deciding on a unit, you may need a bigger one to account for this issue. Ensure your home is well insulated before installation. This will reduce your monthly HVAC expenses and system wear and tear.
Consult with Action Air Conditioning for AC Sizing!
Finding the right AC size can affect indoor comfort, air quality, and humidity. More so, your cooling costs may be higher. Instead, call an HVAC professional. They can evaluate your home, perform a Manual J load calculation, and suggest the right sized unit.
Contact Action Air Conditioning experts for guidance with AC sizing. Our Tampa Bay specialists will ensure your system is the proper size.
At Action Air, we offer superior AC repair and installation services. More so, we operate with reliability and integrity. Hiring our professionals means top-quality AC servicing and enhanced indoor comfort.
Contact us today to speak to an AC technician or to book a FREE estimate!
Originally Published: Apr 7, 2022 Revised and Updated: May 12, 2025