High Efficiency Furnaces
A furnace heater distributes hot air with a ductwork system all throughout the house. A large fan in the furnace blows heated air through supply ductwork to be distributed throughout the living space.
Supply ducts deliver the heated air to different rooms in the house. Return ducts bring cooler air back to the furnace to be reheated.
A gas furnace that's more than 10 years old can be functioning perfectly but only working at 65% efficiency. With the newest technology available, gas furnaces can operate at over 94% efficiency. This means that by upgrading from a 65% efficient gas furnace to a 96% gas furnace, you'll drop your gas bill by 31% just by doing that alone!
Furnaces like this can operate reliably for years, but even when they're operating perfectly, they probably won't be more than around 80% efficient at turning fuel into heat for your home.
Sealed-Combustion Furnaces Are Super-Efficient
A sealed-combustion furnace is so named because the combustion chamber is sealed in order to have more control over the combustion process. The air required for combustion is piped to the combustion chamber from outside the house, through a small-diameter plastic pipe. Gasses that result from combustion are also vented outside through a plastic pipe, with assistance from a small fan. This type of furnace is also sometimes called "direct vent" because it can be vented through an exterior wall. No chimney is necessary.
Sealed-combustion furnaces are super-efficient, earning AFUE ratings of 90% or higher. Nearly all the heat potential of the fuel is extracted, making flue gasses cool enough to be passed through a plastic exhaust pipe. A small amount of water results during the heat condensing cycle, and this condensate is typically piped to a floor drain.
A sealed-combustion gas furnace is a smart choice if you are thinking about replacing an old furnace. In addition to cutting your gas bill, this type of furnace will be safer to operate because there's little danger of backdrafting (which can pull hazardous combustion gasses into your living space).
- Visual inspection. Your technician will check not only the furnace, but also the fuel line, flue pipe, main plenum and ductwork.
- Combustion safety. It’s important to make sure that your furnace is venting correctly, with no danger of combustion gasses getting into your living space.
- Filter check. A dirty filter will be replaced or cleaned. The HVAC tech will also confirm proper filter size and type.
- Furnace cleaning. Removing carbon, soot and other combustion byproducts from the burner and combustion chamber helps to promote more efficient operation.
- Blower check. By listening to your system’s blower and performing a visual inspection, your HVAC specialist will be able to determine if there’s a bearing or balance problem.
- System check. Part of the service includes running the furnace and blower to confirm that the thermostat is working correctly and that warm air is being delivered to your living space.
- Occupant issues. Let your technician know if certain parts of the house are colder or draftier than others. Our experts are trained to identify other factors that affect home comfort and energy efficiency. Even if your furnace is working perfectly, your house may have insulation, air leakage or ductwork conditions that impact comfort and energy efficiency (see sidebar).
Factors That Affect Furnace
- Air leakage. Small cracks & gaps throughout your house allow heated air to escape and cold winter air to enter. As a result, your furnace must work harder to maintain warmth. Sealing these leaks (especially between your living space and the attic) will put less pressure on your heating system.
- Attic insulation. Most homes don’t have nearly enough attic insulation. Sealing air leaks, combined with an attic insulation upgrade, can cut heating costs by 40%.
- Leaky ductwork. Conditioned air that escapes through duct leaks can diminish HVAC efficiency by 20%.
- Duct insulation. Ductwork that runs through a cold attic or crawl space will cool the heated air coming from your furnace. Solve the problem by having this ductwork insulated.