Purchasing a new furnace represents a significant investment in warm indoor comfort. Different styles, technologies and efficiency options may seem daunting, but if you are suitably prepared, you can find a dependable appliance that will provide years of reliable service.

Furnace Types

Furnaces are fuel specific and burn natural gas, propane or fuel oil. Manufacturers produce a variety of models designed to meet various budget, comfort and performance expectations. Furnace technology falls into two basic categories that include:

* Conventional Furnaces: A traditional furnace uses a set of burners and a single heat exchanger to initiate the heating process. Hot waste gas naturally rises and is exhausted through the venting system. Conventional furnaces are the least inexpensive, but the single heat exchanger configuration compromises efficiency.

* Condensing Furnaces: A condensing furnace includes a second heat exchanger that recaptures the thermal energy normally lost in the combustion process. The secondary heat exchanger is constructed from special metal alloys designed to withstand the corrosive nature of condensed exhaust gas. After the additional heat energy is extracted, condensate is drained, and the remaining flue gases are drawn through a PVC pipe and vented outdoors. Most high-efficiency furnace models use condensing technology.

Burner and Blower Operation

Furnaces can be further categorized as single stage, two stage or modulating. Single-stage units are either completely disengaged or operating at full capacity, regardless of the existing indoor load. While a single-stage furnace is the least expensive option, they are also less efficient. A two-stage furnace incorporates technology that provides high and low burner settings. The lower setting saves energy in mild weather, and the higher stage takes over during periods of extreme cold. Modulating furnaces provide the ultimate in efficiency by using microprocessor controls to constantly trim the burner and blower motor. This ensures that the output capacity of the appliance matches the varying indoor load requirements.

AFUE Ratings

When comparing different furnaces, it is important to determine the highest efficiency level that comfortably fits your monthly budget. The Annual Fuel Utilization Efficiency (AFUE) rating was developed by ASHRAE to provide an easy way to evaluate the performance characteristics of competing furnace brands and models. In essence, the AFUE rating identifies the percentage of fuel that is converted directly into heat energy during the burn cycle. For example, a 90 AFUE rated furnace exhausts 10 percent of the fuel it consumes in the form of waste gas. Furnaces are available in efficiencies up to 98.5 percent. Current federal installation standards mandate 90 AFUE ratings for northern climates and 80 AFUE ratings for southern states.

Furnace Buying Tips

A successful furnace purchase and installation is dependant on several important factors that will affect price, comfort and efficiency. Follow these guidelines for a better ownership experience.

* Choosing a Contractor: While the build quality of the unit is important, the installing HVAC contractor will actually have a greater impact on comfort, operating costs and system longevity. Three competitive bids will help establish a price range, but verifying the skill and professionalism of the contractor is more important than a low price. The dealer you choose should employ NATE certified technicians and maintain a fully staffed service department if warranty repairs are required. Referrals from friends and business associates are helpful, and contractor complaints are recorded at the appropriate department that regulates your state’s building trades.

* Load Calculations: Verify that the contractor intends to run a complete set of ACCA Manual J load calculations on your home before making any equipment recommendations. Load calculations help ensure that the equipment will be sized to match the exact heating requirements of your home or office. Avoid contractors that use “rule of thumb” methods for sizing equipment. An over-sized furnace will short cycle, which can degrade comfort, intensify drafts and raise monthly operating costs.

* Buy a High-Efficiency Furnace: In cold climates, a high-efficiency furnace can provide significant savings on fuel costs. It also makes sense to purchase an efficient furnace if you are environmentally sensitive. Look for heating appliances that carry the Energy Star label, which provides assurance the unit meets the strict energy efficiency guidelines established by the EPA.

* Routine Maintenance: A preventative maintenance plan will help ensure your new unit will continue to operate reliably through many heating seasons. Technicians visit your home on a biannual basis and perform a variety of important services designed to improve performance and correct minor issues before they can cause a major malfunction.

The Dependable and Economical Furnace

Modern furnaces provide warm comfort and lower operating costs when compared to models installed just over a decade ago. Homeowners in colder climates with an existing furnace that is 10 years or older may benefit from an upgrade. Those with a standing pilot furnace may want to consider immediate replacement to improve safety and substantially lower monthly heating utility costs.