What Size Mini Split AC Do I Need for My Florida Home?

November 16, 2018

what size mini split ac do i need

First, as a quick reminder, mini split (also called ductless) ACs only cool one room or area of your home.

So, if you’re wanting to cool your entire home, you’ll need to have a professional size each ductless unit according to the room it serves.

That said, regardless of whether you need one room cooled or the entire home, you should always contact a professional to perform a load calculation.

In this article, we’ll explain what a load calculation is and why it is the most accurate way to find what ductless size you should get.

But first, we’ll go over how mini split units are sized...

Want a pro to help you choose a new ductless AC?

How mini split units are sized

Ductless AC units are sized in BTUs (British Thermal Units), which is a measurement of heat. Most residential mini split systems have “BTU outputs” that range from 7,000 to 24,000 BTUs.

The higher the ductless unit’s BTU output, the more heat it can remove from a room in one hour.

That said, you want to make sure that the ductless unit you get roughly matches the amount of heat the room gains over an hour’s worth of time.

If you get a unit that’s too big, you risk paying more for a unit you don’t necessarily need. If you get a unit that’s too small, you risk the unit running non-stop and still not keeping your room cool.

So, how do you correctly size a ductless unit to avoid those problems?

We’ll explain...

The accurate way to determine mini split size: A load calculation

To determine exactly what size ductless system you need, you’ll need to have an HVAC professional perform a load calculation.

When a technician performs a load calculation, they’ll measure how much heat enters the room based on factors like:

  • The number of windows and doors in the room
  • The room’s insulation levels
  • The square footage of the room
  • The room’s proximity to the kitchen
  • The number and type of light bulbs in the room
  • How many people will normally occupy the room
  • The type of flooring a room has
  • The materials used in the room’s construction
  • And more

Because your wallet and comfort depends on accurate sizing, make sure you have a tech perform this load calculation before choosing a ductless unit.

That said, not ALL techs should be trusted with this load calculation. You’ll want to beware of technicians who base their sizing recommendations only on square footage...

Beware of this inaccurate “rule-of-thumb” method

As you look for mini split sizing recommendations online, you may see sources that give you a general, “rule-of-thumb” recommendation based solely on the square footage of the room.

For example, you may see mini split sizing charts like this:

  • 150–200 square feet = 5,000 BTUs
  • 250–300 square feet = 7,500 BTUs
  • 350–400 square feet = 10,000 BTUs
  • 450–500 square feet = 12,500 BTUS
  • 550–600 square feet = 15,000 BTUs
  • 650–700 square feet = 17,500 BTUs
  • 750–800 square feet = 20,000 BTUs
  • 850–900 square feet = 22,550 BTUs
  • 950–1,000 square feet = 25,000 BTUs
  • 1,050–1,100 square feet = 27,000 BTUs
  • 1,250–1,300 square feet = 32,500 BTUs
  • 1,350–1,400 square feet = 35,000 BTUs

However, you don’t want to purchase or install a ductless system only based on these general types of square footage recommendations. Remember: a load calculation takes into account many factors—and square footage is only one of them.

If you skip a professional load calculation and choose a system that just matches the square footage of your room, you’ll likely end up with the same problems we outlined above.

Want a 100% accurate recommendation on what size mini split system you need?

All of our techs are trained and certified to perform a cooling load calculation and will help you find the right size mini split system for your home.

Visit our ductless installation page for more information about what to expect when you hire us.

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