To determine what size air conditioner should be installed in your home, your HVAC contractor should perform Manual J load calculations. Determining the home’s cooling load will tell your contractor what capacity the new air conditioner should be to efficiently and effectively cool the home.
Manual J load calculations should be performed to determine what size air conditioner is needed to cool a home. This calculation takes into account the home’s square footage, windows and doors, building materials and insulation, as well as other factors to accurately determine the capacity a new air conditioner should be.
Air conditioner capacity is measured in tons. This is not a reference to the unit’s weight, but the BTUs (British thermal units) needed to cool a space. One ton is equal to 12,000 BTUs.
Measuring a cooling system’s capacity in tons is a reference to early cooling, when homes were cooled by purchasing blocks of ice. Manufacturers used tons to show consumers an air conditioner could cool comparable to tons of ice, a unit consumers were familiar with.
An air conditioner that is properly sized for the home will provide effective cooling and do so efficiently. When air conditioners are too small for the space, they will struggle to deliver the cooling you need. Your spaces will not be cooled properly, and the unit will run overtime trying to provide the cooling necessary. It expends excess energy, and experiences unnecessary wear and tear, leading to early replacement.
Systems that are oversized cause comfort issues, as they produce more cooling than needed. The system runs short cycles, turning on and off frequently, wearing down components faster. Oversized air conditioners also do not operate efficiently, raising your energy bills.