If you’ve done any research on this subject, you’ve probably seen answers based solely on the room’s square footage. (i.e. “A room that’s 550 to 700 sq/ft needs 18,000 BTUs.”)
Sure, you can use square footage to get a general idea of the size AC you need but don’t use it for an exact answer.
Here’s why: To size a ductless air conditioner correctly you need to take into consideration a lot of factors—not just the size of the room.
Don’t worry. We’ll share some of the factors that determine ductless sizing and how to make sure you get the correct size for your home.
Don’t go off of square footage alone for mini split sizing
Why? Well, your ductless AC needs to be sized according to how much heat the room gains in a certain time. And looking solely at the size of the room won’t tell you how quickly it gains heat.
Example: A 500-square-foot room with lots of windows will need a more powerful ductless AC than a room of the same size that doesn’t have any windows.
That’s because windows let in a lot of heat. But the amount of windows a room has isn’t the only other factor that determines how much heat it gains.
Other “heat gain” factors to consider include whether the room:
- Faces South or North
- Has a door leading to the outdoors
- Is a kitchen space or close to the kitchen
- Has carpet (vs hardwood floors)
- Gets direct sunlight at any point during the day
- Is poorly insulated
- Has average ceilings (8 ft) or high ceilings
- Has any heat sources (fireplace, stove, etc.)
- Is typically occupied by 1 or more people
Sound complicated? Don’t worry. A professional will usually perform what’s called a heat load calculation before they size and install your ductless air conditioner. During this calculation, they’ll take into consideration all the factors listed above and size the unit accordingly.
But be warned: not all HVAC techs perform load calculations.
If your tech gives you a ductless AC size based on square footage alone, you could very well end up with a unit that isn’t properly sized for your home.
Let’s look at why correct sizing for your ductless AC unit is so important in the first place.
Why correct ductless AC sizing is so important
Getting the precise size ductless AC is important because it:
- Saves you money on monthly energy bills
- Prevents frequent repairs
- Extends the life of your unit
- Increases your comfort
More specifically, a ductless unit that’s too small will run at full blast all day and still will struggle to cool the home. This increases your utility bills but also puts a lot of strain on the unit compartment—which leads to frequent repairs and a shortened lifespan.
A ductless unit that’s too big, on the other hand, means you’ll spend more upfront for more cooling power that you don’t necessarily need.
Want to get precise ductless AC sizing? Ask a NJ tech
Want to make sure you get the precise ductless AC size your New Jersey home needs?
We’ll send out a tech to perform a thorough in-home load calculation. Then, we’ll provide a quote for the unit you need—all for free.