How do you know what size HVAC System to purchase?

The size of a heating and air conditioning system will determine its ability to heat or cool and the size of your energy bill.  Oversized cooling systems can be noisy, provide inadequate thermal comfort and can lead to mold and poor indoor air quality while costing you too much.

A commonly accepted old estimate is an HVAC unit should provide one ton (12,000 Btu) of cooling for each 400/500 square feet of area.  Today you have to consider local climate and how well your house is sealed and insulated.  In a very efficient house, one ton can condition 800/1,000 square feet.  Make sure your contractor uses the Air Conditioning Contractors of America (ACCA) Manual J to calculate the proper size of equipment you will need.