Properly Sizing an AC Unit for Your Home

sizing ac unit for home


If you live in the Chandler, Arizona area, you know air conditioning is not a luxury but a necessity. If you own an older home that needs a new HVAC unit, or are installing one for the first time in a new home, one thing you’ll need to know is what size unit you need.

Buying an air conditioning unit should not be taken lightly, and purchasing one that is the wrong size can make your home’s temperature uncomfortable or cost you more than you bargained for on your home’s electricity bill. An HVAC unit that is not large enough will have to work overtime and likely won’t keep your home cool enough, and one that is too large will use up excessive energy without providing the consistent temperature you expect when you set your thermostat.

Determining the proper size AC unit for your home is a task best left to a knowledgeable, experienced HVAC repair and installation specialist. One of the reasons your choice of air conditioning specialist is so important is their ability to properly design a system, an important factor of which is the size and strength of the A/C unit itself.

Calculate Your Home’s Square Footage

Generally your home’s accurate square footage should be available through your property tax statement, because the county’s auditor’s office uses this information when calculating what you owe every year. The square footage of your home is necessary when deciding how powerful a unit you need.

Square footage isn’t the only relevant factor though. A good contractor will also take into account the height of your ceilings. They should break down the number room by room and then add all the rooms together while also factoring in your ductwork and distance of the rooms from the unit itself.

Follow the BTU Guidelines

Luckily, the United States Department of Energy has provided guidelines for BTUs (British thermal units) to help homeowners double check the work of contractors by giving you a rough idea of the proper size HVAC unit you need for your central or room air conditioner.

btu guidelines

For rooms shaded heavily, decrease capacity by 10%
For rooms exposed to lots of sun, increase capacity by 10%
If the unit will be placed in a kitchen, increase capacity by 4,000 BTUs
If more than two people regularly occupy the room, add 600 BTUs for each additional person
Don’t include areas that don’t need to be cooled such as a basement or garage

Heating and Air Conditioning in Phoenix

Western States Home Services knows how important air conditioning is to residents of Phoenix, Chandler, Ahwatukee and the surrounding areas. We specialize in air conditioning repair as well as new air conditioning systems and 24/7 emergency air conditioning service. Contact us today to learn more.