New furnace efficiency requirements to change
GREATER AKRON — The Federal Trade Commission requires all furnaces to be labeled with its annual fuel utilization efficiency (AFUE) rating so consumers can compare heating efficiencies of various models, according to the U.S. Department of Energy (DOE).
The minimum allowed AFUE rating for a noncondensing fossil-fueled, warm-air furnace is currently 78 percent, except for those designed and manufactured specifically for use in mobile homes, for which the minimum AFUE is 75 percent, according to the DOE.
Beginning May 1, all indoor gas furnaces and mobile home gas furnaces installed in the northern half of the United States will be required to have a minimum AFUE of 90 percent, according to the DOE.
Furnaces that can match that rating include all electric units and condensing furnaces.
All-electric units have AFUE ratings between 95 percent and 100 percent, but the cost of electricity in most parts of the country makes all-electric furnaces or boilers an uneconomic choice, according to the DOE.
DOE officials state a condensing furnace condenses the water vapor produced in the combustion process and uses the heat from this condensation. The AFUE rating for this furnace can be more than 10 percentage points higher than a noncondensing unit and it costs more, but they can save money in fuel costs over the approximately 15- to 30-year life of the unit.
When shopping for a high-efficiency furnace, the DOE suggests consumers look for a sealed combustion unit, which brings outside air directly into the burner and exhausts flue gases directly to the outside without the need for a draft hood or damper. Furnaces that are not sealed-combustion units draw heated air into the unit for combustion and then send that air up the chimney, wasting the energy that was used to heat the air. Sealed-combustion units avoid that problem and also pose no risk of introducing dangerous combustion gases into a house.
DOE officials caution, however, that high-efficiency sealed-combustion units generally produce an acidic exhaust gas that is not suitable for old unlined chimneys, so the exhaust gas should either be vented through a new duct or the chimney should be lined to accommodate the acidic gas.
Old coal burners that were switched over to oil or gas are prime candidates for replacement, as well as gas furnaces with pilot lights rather than electronic ignitions.
Retrofitting a not-too-old furnace can also increase its efficiency and improve its safety, DOE officials added, but the costs of retrofits should be weighed against the cost of a new one, especially if replacement is likely within a few years or if you wish to switch to a different system for other reasons, such as adding air conditioning.
DOE officials state that any time you retrofit or replace a gas or oil heating system, the chimney system should be examined to ensure it functions properly and the gas heating system is properly ventilated.
Energy-efficiency upgrades and a new high-efficiency heating system can often cut fuel bills and a furnace’s pollution output in half, according to the DOE. For example, upgrading your furnace from 56 percent to 90 percent efficiency in an average cold-climate house will save 1.5 tons of carbon dioxide emissions each year if you heat with gas, or 2.5 tons if you heat with oil. Also, going from 50 percent fuel efficiency to 90 percent is estimated to save $44 annually for every $100 of fuel costs. Going from 70 percent to 90 percent would save $22, and from 80 percent to 90 percent, the savings would be $11 for every $100 in fuel costs annually.
Before buying a new furnace or modifying an existing unit, the DOE suggests homeowners improve the energy efficiency of a home and then have a heating contractor size a furnace for the home. These improvements will save money on a new furnace or boiler because you can purchase a smaller unit.
For more information, visit energy.gov/energysaver/articles/furnaces-and-boilers.
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