High-Efficiency Heating System Tips
Selecting the heating equipment that is right for you isn't always easy. Below are some tips and information you should keep in mind when looking for high-efficiency heating systems.
Guide to Ratings
The Annual Fuel Utilization Efficiency (AFUE) rating is set by the U.S. Department of Energy under the National Appliance Energy Conservation Act of 1987. The rating is expressed in percentages. The higher the AFUE rating, the more efficient the heating system and less energy is needed to heat your home or hot water.
The minimum efficiency standard for furnaces is 78 percent AFUE, for gas-fired water boilers is 80 percent AFUE, and the minimum for gas-fired steam boilers is 78 percent AFUE. For example, a new, high-efficiency furnace with a 94 percent AFUE provides 94 cents worth of heat from every energy dollar.
Annual Savings: Simple Payback
If you install a residential warm air furnace at 90 percent AFUE vs. 80 percent AFUE, the estimated annual savings in energy costs is $115 with a simple payback of 2.6 years. (Analysis of annual savings provided by the Consortium of Energy Efficiency, a national non-profit organization)
Condensing furnaces with efficiencies over 90 percent offer the most energy savings. These furnaces achieve 90 percent AFUE rating by sending flue gases through a secondary heat exchanger. This device further extracts heat that is usable energy for your home. Remaining flue gases then exhaust outdoors through a special plastic-type vent pipe inserted through the wall of the home. This "direct-vent" piping configuration also draws in outside air for combustion. Since indoor air is not used in the combustion process, cold air leakage (infiltration) is reduced--an added energy savings.
In addition, it is important to realize, that when installing new furnaces, the chimney must be properly lined to avoid corrosion that can occur during condensation. This is typically the case when replacing equipment in existing construction.
Most new high-efficiency gas furnaces carry up to a lifetime warranty on the heat exchanger. Many manufacturers and contractors also offer warranties from two to five years on all parts.
A boiler can last between 20 to 30 years, so choosing an efficient model can reduce long-term costs. Condensing boilers - the most efficient - extract heat by condensing water vapor from flue gases.
Sizing Your Heating System
Sizing your heating system should always include the help of a qualified heating contractor. A system that is too large can be wasteful and a system that is too small can't provide proper comfort. A qualified heating contractor can help you estimate the heat loss in your home by evaluating the insulation levels and the square footage of wall, roof and floor space exposed to the outside. Then, using the outdoor and desired indoor temperatures, they can calculate the appropriate capacity for your new heating system, measured in BTUs (British Thermal Units) per hour.
Choosing a Plumber/Heating Contractor
A reliable plumber or heating contractor will inspect your home and offer an estimate, provide a survey and a heat-loss calculation. They should also supply you with a written proposal clearly outlining the work to be done with the agreed upon price. Many plumbers and contractors also offer other services as well.
Please remind your contractor that rebate eligibility is based on the manufacturers' equipment/model AFUE ratings and not Energy Guide Labeling stickers. Equipment AFUE minimums are:
- Furnaces greater than or equal to 90 percent AFUE
- Boilers greater than or equal to 85 percent AFUE