A system that’s too small or too large won’t operate as efficiently as possible. That means higher monthly utility bills, an increase in maintenance and repairs and a reduction in the lifespan of the unit. If your contractor doesn’t perform a load calculation in your home, it’s impossible to know for sure that any HVAC system purchased is right for the house. An experienced HVAC contractor knows that in order to properly conduct a load calculation it’s important to collect eight important factors. That includes the climate where the house is located, the size, shape and orientation of the house, the level of insulation throughout the house, total area and types of windows, air inflation rates, number and ages of family members, types of major appliances and lights. In addition, the contractor should ask if you had any particular issues with the unit.