
Furnaces
Furnaces are the most common residential heating system in the U.S.
Earning the ENERGY STAR means products meet strict energy efficiency
guidelines set by the US Environmental Protection Agency and the
Department of Energy.
ENERGY STAR qualified furnaces have an annual fuel utilization
efficiency (AFUE) rating of 90% or greater, making them about 15% more
efficient than standard models.
Saving energy prevents pollution.
Though these products can be more expensive to purchase up front, the
cost difference will be paid back over time through lower energy bills.
When buying new equipment, sizing and installation are as important as product quality.
- You can get
better heating and cooling performance at home with ENERGY STAR home
sealing (insulation and air sealing) and duct sealing.
- Consider regular maintenance to maintain your heating and cooling system performance.
Sizing and Installation
Your new heating and cooling system should be a custom fit for your
home. Sizing and a handful of other installation practices can
dramatically affect how well your new equipment will deliver comfort
and savings. Expect to pay a little more for a good contractor who
follows these practices.
- Calculate the size of equipment
- Seal and insulate ducts in attics and crawlspaces
- Check and correct air flow
- Proper refrigerant charging
- Equipment placement
Calculate the size of equipment
For starters your new furnace, boiler, heat pump or air conditioner
should be sized to fit your home. You can request a copy of the design
load calculation used to determine the right size of equipment for your
home.
A good contractor will not size your equipment solely on the square
footage of your house or assume that your existing equipment was sized
properly in the first place. Proper equipment sizing is based your
home's heat loss during cold weather and heat gains during warm
weather.
To complete the design load calculation the contractor will need to
take measurements during the initial visit to your home and ask you
some questions. The calculation is usually done using software, and
should be based on professional guidelines such as Manual J from the
Air Conditioning Contractors of America (ACCA) or similar method.
Oversized equipment can cause reduced comfort and excessive "air"
noise. Over sizing will shorten the life of the equipment by causing it
to cycle on and off more frequently than a properly-sized unit.
Undersized equipment, with airflow that is too low, can reduce the
efficiency of the air distribution and accelerate wear on system
components, leading to earlier failure.
After the design load calculation is completed, ducts, supply
registers, and return grilles can be sized and selected using
professional guidelines in ACCA's Manual D or similar method.
Seal and insulate ducts in attics and crawlspaces
If you're installing a central air conditioner, furnace or heat pump,
ask your contractor about the condition of your air ducts. A good
contractor should be able to test your air ducts to identify and seal
leaks.
Duct sealing should be done by a professional using mastic, metal-backed tape or aerosol-based sealing.
In some instances, your contractor may advise you that it is necessary
to replace or add ducts. If there are insufficient supply registers or
return air grilles in your home, it may be necessary to install
additional ducts to accommodate the need for registers or grilles. When
possible ducts should be located within conditioned space. If the ducts
must be in unconditioned space (attic or crawlspace) they should be
insulated.
Check and correct airflow
- For central air conditioners, furnaces or heat pumps there is an optimal air flow for comfort and savings.
- If airflow is too high, duct leakage increases and the temperature at the register is not sufficient for optimal home comfort.
- If airflow is too low, distribution efficiency drops and accelerates the wear on system components leading to premature failure
- A good
contractor will test the air flow of your heating and cooling system
and make adjustments for optimal performance. Typically, testing and
adjustments should be done after duct leakage repairs have been
completed.
Proper refrigerant charging
If your are installing a new central air conditioner or heat pump you
should know that recent field studies suggest that approximately 75% of
installed cooling equipment may have incorrect amount of refrigerant.
Incorrect refrigerant level can lower efficiency by 5 to 20% and can
ultimately cause premature component failure, resulting in costly
repairs that could have been prevented. A good contractor will use one
of three methods, recommended by equipment manufacturers, to verify the
correct refrigerant level. These methods include super-heat,
sub-cooling, or weigh. Ask your contractor how they verify the
refrigerant level is correct.
In addition, you should know that since 1992, in order to protect the
earth's atmosphere (ozone layer), all technicians must be certified to
handle refrigerant. Ask them to show you proof of refrigerant handling
certification.
Equipment placement
Placement of new equipment is unique for every home, but a good
contractor should follow manufacturer's installation instructions for
best results. For example, Indoor equipment should be installed in
conditioned space, or a space that is well insulated. The Outdoor
compressors should be placed out of the sun and kept free of debris.
Equipment should be installed in an accessible area for easy
maintenance. Allow plenty of room for free airflow on all sides of the
equipment. Thermostats should be placed away from direct sunlight,
drafts, doorways, skylights and windows.
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