Ask for referrals. Ask people you know for references about the contractor’s installation performance, and if the job was completed on time and within budget. You also can contact local trade organizations for members in your area.Get written, itemized estimates. Do not expect or accept a quote over the phone. When comparing contractors’ estimates, be sure to compare cost, energy efficiency and warranties. A lowest price may not be the best deal if the equipment being offered is not the most efficient—your energy costs could be higher.Look for evidence of quality work, rather than focusing on lowest price.Ask for a load calculation, which uses design information on your home to calculate equipment size. Do not use an HVAC contractor who wants to size your unit solely on the square footage of your home.Get it in ink. Sign a written contract before work gets started. This protects you by specifying project costs, model numbers, job schedule, and warranty information.Ask for high-efficiency certified equipment. These products meet strict guidelines set by the U.S. Environmental Protection Agency and offer significant long-term energy savings.Ask for verification from the contractor that the system will be installed according to manufacturer’s specifications.