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How Do I Size An HVAC System?

When it comes to purchasing an HVAC system, you cannot just choose the cheapest model and be done. Your HVAC system needs to be the proper size for your home. Improperly sized units’ manifest issues very quickly. You may notice a unit too small for your home sucks up energy as it runs constantly to desperately try to get your home to the right temperature. Yet, a unit too large will short cycle. This not only uses more energy, has reduced heating and cooling power, and adds extra wear to the system.

How to Size an HVAC System for Your Home?

Unfortunately, there is no easy answer as to what size HVAC system you need. It is not necessarily just a measurement of square footage, but there are several different variables.

Home Placement

The placement of your home plays a role in your size needs. If a home is in full sun all day, it will require a unit with more cooling power whereas a full shade home may need more heating power.

Home Age

It is not so much that old homes are less energy efficient, which they can be, but older homes may only be able to host certain sized HVAC systems without retrofitting. The electrical system of the home also may only be able to handle certain sizes as well.


Windows let light and heat in. As such, the number and condition of the windows in your home play a factor on what size of HVAC system you need. Furthermore, the more sun exposure they get during the day has an effect as well.


Your home, and the insulation it uses, gives your home an R-value, which is how well it holds and releases energy. This is crucial in the calculation of a new HVAC system.

This all sounds quite complicated, and it can be. Usually, you will want to contact an HVAC technician to help you calculate the load size for your HVAC system of choice. Are you looking to install a new heating or cooling system? We can help. Contact us today to see what Minnesota Heating & Air Conditioning can do to help.