It isn't uncommon to have multiple HVAC units installed in homes to help keep temperatures consistent. It is especially helpful in larger homes or homes with multiple levels where it is harder to keep the upper floors cool in the summer.
Estimating How Many AC Units To Install
Many people think calculating how many HVAC units to install is simply based on the square footage of their home. In reality the optimal number of units, and which sized units, are based on many factors specific to your home.
How many windows face certain directions, how well your home is insulated, the age of your home and even how many trees and shrubs are in your yard are all taken into consideration.
The climate in your area also plays a role in determining the optimal number of units to install. Summer in Richmond is very hot and humid and we need more cooling power than a homeowner in Vermont for example.
While there isn’t a one-sized fits all formula to tell you exactly how many AC units are best for your home, there are tools that can help estimate. This calculator from This Old House or this worksheet from cooloff.org can give you a general idea how many units and what sizes to consider.
What Size AC Units Should I Have Installed?
The AC units most often installed in residential homes range from 1 ton to 5 ton units. In this case the term ton doesn’t refer to the weight of the unit, but how much heat the air conditioner can remove from the house in an hour. The larger the tonnage the more cooling power the unit provides. AC units do go larger than 6 tons, but anything larger than 5 tons is generally reserved for commercial installations.
Most homes won't require multiple 5 ton units to keep the home cool, so don’t assume that bigger is always better. In fact, installing a system that is too large for your home still won't cool your home effectively or efficiently.
Getting the right number of units, and the right tonnage is critical so it is best to consult a professional. A true professional will not try to sell you more than you need, but provide the best solution by assessing your home, as well as the needs of your family.