Experts say the first step in buying a new furnace is choosing the contractor who will install it. Your contractor should offer you a choice of furnace models with different efficiency ratings and should provide an estimate of annual operating costs for each one. Most contractors specialize in working with certain brands of furnaces, and some shops work with only one particular brand. This can be an advantage, because it means the contractor has most likely received specialized training from the manufacturer. However, it means that your furnace choices will be limited to that one brand. If you get an estimate from a contractor who deals only in one brand, get estimates from other contractors as well, making sure the furnaces they recommend are equivalent in size and efficiency.
Contact several contractors and get an estimate in writing from each one. Most sources recommend getting at least three estimates. If you already know a reputable HVAC contractor, start your search with that person. You can also solicit references from friends, neighbors and co-workers. Your local utility can also be a good place to look. Focus on local companies, and look for contractors who are licensed and insured.
Another tip from experts is to steer clear of companies that offer to give you an estimate over the phone. A reliable estimate must be based on a thorough survey of your home. The contractor should consider such factors as the size of the house, insulation levels, number and type of windows and the climate in your area. He or she should inspect your ductwork (if any) for air leaks and insulation level and measure airflow levels. The contractor should also ask you about any problems you have had with your existing heating system. Based on all this information, the contractor can perform a heat-load calculation to determine the proper size of your new furnace.
A contractor should never base this decision on the size of your existing furnace. Many homes have furnaces that are too large, partly because sizing methods have improved and partly because buildings have become more energy efficient. A furnace that is too large will not only cost more to install and operate, but it may not heat your home as evenly as one that is properly sized. A good contractor should evaluate your entire heating system and make appropriate suggestions for improving the overall energy efficiency of your home. This may allow you to purchase a smaller furnace and save money.
When you get estimates from contractors, ask them for customer references. A successful furnace contractor should not have any trouble providing these. Call each person on the reference list and ask them whether they were happy with the contractor's performance, including installation and service. Ask whether the job was completed on time and on budget, and whether they would have any hesitation about recommending this contractor. If a reference is unwilling to discuss a contractor or gives a lukewarm recommendation, be wary. Customers may be unwilling to give an outright negative reference for someone they may need to deal with again in the future. You can also check up on your contractor's past record by contacting your local Better Business Bureau.
Several other factors may also play a role in your choice of a contractor. You should also ask about the credentials of the technician who will be performing the furnace installation. Most sources recommend that the installation be performed by a technician who is certified by North American Technician Excellence (NATE). Home-improvement expert Danny Lipford recommends that the owner of the HVAC shop should "be involved with the system design and either participate actively in the installation or inspect it when it's done." Also, you should ask whether the installation standards established by the Air Conditioning Contractors of America (ACCA) will be followed. These standards require contractors to follow and document certain steps, such as sizing the furnace correctly, choosing compatible components and testing the operation controls.
The written estimate you get from each contractor should spell out all the details about the installation. It should describe the equipment to be installed, the work to be done, the costs for materials and labor and the payment schedule. It should also describe the equipment and installation warranties and provide a firm date for completion of the project. Make sure bids include all costs associated with the project, including permit fees (if required). Compare all your estimates and make sure that they cover the same work and the same type of equipment.
It may be tempting to go with the contractor who offers you the lowest estimate, but experts warn that price is not the most important consideration. For example, very low bids may not include routine services and customary warranties. If one contractor's bid is dramatically different from the others, don't hesitate to ask why. It's possible that this contractor has noticed something that others missed -- or vice versa.