Any contractor you're considering also should offer these products and services: Heat-loss calculation. This process estimates the Btu capacity needed to heat or cool your home. The calculation should include the amount and type of insulation in the walls, attic and floors of your home, as well as the type, number and location of windows and doors. This data is combined with your regional climatic conditions to determine the size unit you need. Software has made these calculations relatively easy. HVAC technicians who don't perform them often specify oversize equipment to be safe. That's dollars out of your pocket now and each time you get an utility bill. Energy advice. When sizing an HVAC unit, a good contractor will advise you of energy upgrades, such as adding another layer of insulation to the attic. These may allow you to buy a smaller HVAC unit.
Efficient equipment. Although it's often not cost effective to buy the most energy-efficient unit on the market, there are minimums to shoot for. Here's what a contractor should offer: An air-conditioning unit (if below five tons) with a SEER of 10, preferably 12
A high-efficiency natural-gas heater with an AFUE of around 90 percent
A fuel-oil burner with an AFUE of around 85 percent
A heat pump with an EER of 12 Automatic controls. A setback thermostat ($40), which contains a timer, should regulate all HVAC systems. Payback calculations. A quality HVAC contractor will show you payback calculations for the various units he offers, and those calculations should give you estimates of seasonal operating costs. Variables the contractor will use in his calculations include your regional heating or cooling load, the heating or cooling capacity of the units you are considering and the costs of various types of energy, so you can compare the costs of electric, gas and oil. Once you receive itemized estimates, you compare costs and do some of your own research on equipment. Start by visiting the U.S. Department of Energy or websites (the latter site is fee-based), or contact your utility company for comparative lists. Look at operating efficiency and costs as well as consumer-rated reliability. Then compare your knowledge of the contractors involved and make your decision.