It’s no secret that replacing your heating and cooling system can be a headache. When’s the right time? What kind of system is best? Where can I find a reliable contractor?
Because the right contractor remains the critical cog in this process—for determining the type and size of the unit needed, explaining your options, and proper installation—consider these tips before making a selection.

Ask around
What are the contractor’s licensing and qualifications? Is the contractor a member of state and national contractor associations, such as Air Conditioning Contractors of America? Is he or she adequately insured?

Almost 50 percent of your energy bill comes from an HVAC [heating, ventilation, and air conditioning] system, so it is important to have the right person put in and maintain the equipment.
Word of mouth provides a valuable resource, so ask neighbors and friends if they can recommend a good contractor—or if there’s someone you should avoid. And remember to check on what a prospective contractor guarantees and whether any follow-up services, such as a maintenance agreement, are offered.

What the contractor and you should do
After you ask these questions, a good contractor should start by inspecting your home and old system and then explaining your options.
Be sure to get the estimated annual operating cost of the proposed HVAC system at different efficiency levels, as recommended by the U.S. Environmental Protection Agency’s ENERGY STAR® program. Air conditioners are measured by Seasonal Energy Efficiency Ratio (SEER) and Energy Efficiency Ratio (EER). SEER is calculated by dividing the amount of cooling provided during a normal year by energy used—the higher the SEER, the more efficient the unit. EER helps if you want to know how a system operates at a specific temperature.  This will help you to determine the total cost over its lifetime. Ask for three written estimates of the work: what is being done, what equipment is being provided, and when installation will begin and be completed. A contractor should explain what is included—the best value may not come from whoever offers the lowest price.

NATE certification
Finally, consider looking for someone who is NATE (North American Technician Excellence) certified. Remember, though, because NATE is a voluntary process, a contractor isn’t necessarily a bad installer if she or he doesn’t have the credentials, contends Brian Sloboda, a senior program manager specializing in energy efficiency for the Cooperative Research Network, an arm of the Arlington, Va.-based National Rural Electric Cooperative Association.
NATE-certified contractors will have gone through the steps to prove they have the skills necessary for their job, although it isn’t a guarantee that they are good. But it does provide some extra evidence to help consumers know that the person they’re hiring has been tested.
Sources: Madeline Keimig, Touchstone Energy® Cooperative; U.S. Department of Energy, U.S. Environmental Protection Agency.