Choosing a good contractor to install a new furnace or central air conditioner can be as important as the equipment you choose, because proper installation and maintenance is needed for the equipment to operate safely, reliably, and at maximum efficiency. Here are some suggestions for selecting a contractor, adapted in part from Contracting Business magazine.

• If you already know a reputable heating and air conditioning contractor, that is a good place to start. If you don't, friends and relatives in the area can often give you recommendations.
  
  
• Most leading residential contractors belong to the Air Conditioning Contractors of America (ACCA) or the Sheet Metal and Air Conditioning Contractors' National Association (SMACNA). Both sites provide listings of heating, cooling, ventilation and refrigeration contractors in your area. Look for contractors whose technicians are certified by North American Technician Excellence (NATE) and/or partnered with ENERGY STAR.
  
  
• Do not give your business to a company offering to give you an estimate over the phone without ever looking at the job to be done.
  
  
• A well-trained, up-to-date contractor will not try to discourage you from purchasing high-efficiency equipment. Less-qualified companies may not keep their employees current with the latest technology, and therefore they may discourage you from new and better designs.
  
  
• A good estimator will do a survey of your home and base his or her proposal on a heat-load calculation (or cooling-load calculation for air conditioning).
  
  
• Many furnaces and central air conditioners are not properly sized for the homes they serve, because of improper sizing years ago and/or energy efficiency improvements to the building since the old equipment was installed. Better contractors will not use your existing equipment to size your new heating or cooling system.
  
  
• A good estimator should also ask about any heating or cooling problems you have had with your old equipment, and offer understandable explanations or solutions.
  
  
• Using their heat-load and/or cooling-load calculations, good contractors should be able to estimate the annual operating costs (energy bills) for the equipment they are proposing for your home.
  
  
• A good company will give you a written bid (or proposal) outlining the equipment to be installed, the work to be done, and the price, including labor costs.
  
  
• We suggest you get estimates from multiple contractors, but try not to let the lowest price be the main reason for selecting a contractor. Better contractors may charge more, but they probably offer greater value. Be skeptical of extremely low bids; those contractors may not be including all routine services and customary warranties, or they may be trying to unload outdated or unreliable equipment.
  
  
• Reliable contractors are professional. Their people are prompt and courteous. How a company treats you now reflects how they will treat you if there is a problem. They should have an office or shop facility, and they should not be ashamed to have you visit them. An office or shop is an indication that the company has been in business and intends to remain in business.