What AC Unit Size is Best for My House?

March 24, 2019 by Air Care in FAQ, Installation, News 1252

If am going to install a new HVAC unit at my house what size is the best or the right size?

An AC system that is too small will not sufficiently cool your house. On the other hand, a system that is too large will not be energy efficient because an over-sized air conditioning system will cycle (turn off and on) more often than necessary. This cycling wastes energy and sometimes places undue strain on the system compressor. One of the advantages of working with a Pro Partner, such as Air Care, is that we can study your home when we come out to give you an install estimate. At that time, our technician can determine the optimal size for your home by analyzing your home structure, existing vents and ductwork, and your cooling requirements / issues. Additional variables we consider when sizing a new unit for a home are:

Window dimensions and sun exposure
Floor space
Insulation
Heat emitting appliances
Percentage of your home’s exterior shaded by either trees, plants, or shrubs.

HVAC Unit Basic Math

Are you looking to determine the approximate size of your new HVAC system? Then you can use the following calculations to help make a ballpark estimate / educated guess for the size of your new system.

Step 1 – What is the square footage of your home?

If you do not know the square footage of your home, you can check Zillow or the County Property Appraiser website for the county in which you live. (see links below)

Step 2 – Do you have high ceilings in your home?

If yes, then multiple the square footage of your home by 1.25.

Step 3 – Multiple by 25 BTUs

The unit used to measure energy used for heating / cooling is the British Thermal Unit, or BTU. The approx. amount of energy used to cool a square foot a home in Florida is roughly 25 BTUs. Consequently, multiply the number you calculated in Step 2 by 25 to get your home’s base BTU measurement.

Let Air Care Do the Math

Air Care offers a free written estimate on installs of new HVAC systems. When we size AC units for home, our technicians use a more precise calculation, a method called the “Manual J calculation.” This method gives homeowners a more precise analysis of HVAC unit sizing for their home. Please call us at 727-449-2699 to schedule a free in-home written installation estimate.

Are you an engineer homeowner or an HVAC professional looking for more detailed information on this topic? Then, we recommend you read the “Strategy Guideline: HVAC Equipment Sizing” published by the U.S. Department of Energy.