Heating and cooling your home accounts for approximately If you decide to repair your furnace, look for a heating
44% of a ho mes energy use. Deficiencies in these systems professional who has experience with your type of heating
can make a great impact on how much ext ra money you system.
spend on your utility b ills. Making sure these, systems are
running in top shape can increasing the efficiencies and you Buying a new furnace
tremendous amounts of money. Whenever you purchase a new heating system the primary
factors to consider are: the type of fuel you are going to use,
It is impo rtant periodically to evaluate your heating system. how the heat will be distributed throughout the house, what
It is especially important not to wait until a crisis occurs. size furnace to buy, and the efficiency rating.
In assessing your present system, co mpare it with new, Type of fuel
improved systems. An old furnace, even when it’s running If you have a choice of fuels, you
well, may ext ract only 60 per-cent of the availab le heat will want to consider which is the
fro m the fuel over the heating system. That means only 60 most affordable in the end.
cents of your heating dollars is going into the house as heat;
the rest is going up and out the chimney. In contrast, the Heat distri buti on
best of the new furnaces are so efficient that they waste less Consider the opportunities offered
than a nickel o f very dollar spent. by different distribution systems.
The primary difference between
Repair vs. repl acement ‘furnaces’ and ‘boilers’ is that a
Your first step is to decide if your furnace uses air to distribute heat
present furnace operates properly. If throughout the house and a boiler
your furnace is old, or has a serious uses water. Forced air systems allo w easy installation of
malfunction that will cost several traditional central air conditioning, since the same ductwork
hundred dollars to fix, it may be wise to can be used to distribute warm or cool air. Th is makes a
replace it. forced air systems more economical if you plan to install
central air conditioning.
As a general rule of thumb, if your furnace is mo re than ten
years old and costs more than $500 to fix, it should Furnace size
probably be replaced in place of repair. If your furnace is Furnace size is almost as important as the efficiency rat ing.
old but not broken, deciding when to replace it can be The most common mistake is buying a heating system too
difficult. Average life expectancy of furnaces in homes large fo r your home. Remember, the notion that ‘bigger is
today is between 16 and 20 years. If your furnace is close to better’ does not apply to heating or air condition ing
this age or older, begin shopping. This holds true for boilers systems. If your heating system is oversized, it can create
as well, although boilers have greater life expectancy, 30 temperature swings in your home and reduce comfort.
years. Be prepared to replace your furnace or boiler. Unfortunately, there are no simple ru les for furnace sizing.
Shopping for a replacement furnace in an emergency does We recommend that you ask a heating professional to do a
not allow t ime to get fair market pricing. The design of your heat loss calculation to ensure that you are buying the right
house and the size of your utility b ills may be deciding size. Many municipalities require a heat loss calculation at
factors. Generally, if you have a large house with high the time the contractor requests a permit to install your
heating bills, it could be more cost-effective to purchase a heating system. A heat loss calculation includes factors
high efficiency furnace now rather than wait for your such as the window area, type of windows, insulating
present furnace to wear out. proper-ties of the wall, and the amount of heat loss through
air leakage. Discuss any remodeling plans with your
Residential Energy Assessment Program Heating Systems
contractor. Ask any contractor who bases estimates solely New high efficiency furnaces
on the square footage of your house to do a true heat loss A high efficiency furnace with sealed co mbustion or
calculation. If you are considering buying a central air mechanical venting saves you money over the life o f the
conditioner at the same time as a new furnace, be sure that furnace, reduces the chances of back-drafting furnace gases
the air conditioner is sized properly. If your cooling unit is into the home, and contributes to a healthier environment.
sized too large, it will not do a good job of dehumid ify ing. The economic benefits can be surprising. For examp le, if
you change from a fu rnace with 60 percent efficiency to a
Furnace efficiency furnace with a 90 percent or h igher efficiency, it is possible
We recommend that you look for a fu rnace with an AFUE to save 30 to 40 percent on your annual fuel costs.
(annual fuel utilization efficiency) of mo re than 90 percent Depending on whether you heat with gas, oil or propane,
and a sealed combustion system. In addit ion, consider savings could be $250 to $500 per year. Fro m a safety
buying a furnace with a variable speed blower motor to standpoint, efficient fu rnaces and water heaters with
improve electrical efficiency. Our recommendation for mechanical venting or, better yet, a sealed co mbustion
boilers is an AFUE of 84 percent or greater, with a sealed system, greatly reduce the danger of backdraft ing.
combustion system or a mechanical exhaust. If a high
efficiency heating system is out of your price range, Maintai ning your furnace and duct system
consider those furnaces and boilers with mechanical Keeping your heating system well maintained and properly
venting. The more efficient a unit, the more heat (Btus) you adjusted is important for every system regardless whether it
will receive fro m your fuel. Remember, however, that an is new or o ld. A qualified service person should
efficient heating system is only one co mponent contributing periodically check, clean, and tune your furnace, not only
to your home’s efficiency. for energy efficiency but also for safety. Make sure the duct
is sealed. Sealing ductwork with alu minized duct tape can
Choosing a heating contractor improve the efficiency of your cooling system and reduce
A new heating system costs heat loss. It may be a good idea to ask a heating specialist to
money – anywhere fro m $2,000 balance the heating system. All o il and gas furnaces should
to more than $4,500. When be tuned every year, unless the manufacturer d irects
buying a new heating system, you otherwise. Do-it-yourself maintenance measures include:
should compare prices. It isn’t
unusual for bids to differ by as • Change the furnace filter once a month.
much as several hundred dollars. • Clean the blower at least once a year.
You should receive written bids • Make sure registers and furniture or draperies do not
on the cost of equipment and block rad iators.
installation fro m at least three • Bleed radiators, baseboard heaters, and other systems
contractors, and ask each for the that use heat radiation once a year.
names of customers who have had their heating system for
a few years. When evaluating bids, look at prices but also Operating your furnace
pay attention to and compare quality, energy savings, and How you operate your heating system affects how much
warranties. If you are putting in a high efficiency furnace or energy you use. Follow these suggestions to lower your
boiler, ask if the contractor has special training in th is type heating bill:
of installation. If you think your old heating system is
covered with asbestos insulation, discuss this with the • Turn down thermostats in unused rooms, at night, and
contractor. Make sure they follow the proper procedures in when you are going to be gone for more than four hours
dealing with asbestos removal. during the day. Automatic setback thermostats can do this
A new heating system must be installed properly. Furnaces • Have your heating contractor adjust the fan thermostat for
and boilers should be tuned and a combustion efficiency an efficient on-off temperature.
test performed after installation. Make sure the contractor • Close off both the supply and return registers to the
is fully bonded and insured. basement or other unused rooms.
The equipment and alterations that are known to be safe and
effective in some situations are:
Residential Energy Assessment Program Heating Systems
some cases, the chimney liner may have to be replaced to
Automatic setback thermostat reduce the risk of backd rafting. If you have a gas furnace
Lowering the thermostat at night or with a masonry chimney, you must have a metallic liner.
during the day while you are away will Have your contractor inspect for this.
save one percent for every one-degree-
Fahrenheit per eight hours of setback. Be wise: weatherize
Manually resetting the temperature, Whether or not you buy a new furnace, it is a good idea to
twice a day will not cost anything, but weatherize your ho me. Adding insulation and strategically
this can be inconvenient. Instead, you can get an automatic caulking and weatherstripping will make your ho me more
setback thermostat to do the work for you. So me are comfo rtable, save energy, and reduce the size of the furnace
relatively inexpensive and pay for themselves in a very you need if you are going to purchase a new system. As
short time. your heating load decreases, the size and cost of a heating
system required to meet that load also decreases. You might
Vent dampers consider having a home energy efficiency analysis
This device automatically b locks off the vent pipe after the performed. So metimes referred to as an energy audit,” this
burner shuts off. This prevents warm air fro m escaping up is a detailed examination of your home’s energy use often
the vent when the furnace isn’t running. On the average, provided at no or low cost by utilit ies. Check with your
you will save about six percent on your fuel b ills with a utility to see if it provides an audit. It is important to
vent damper. remember that if you tighten your home you must make
sure that you have adequate indoor ventilation.
Dampers are either thermally or electrically operated.
Thermal dampers, the cheaper but least effective of the two, Bibliography
open and close by the change in exhaust gas temperature. M innesota Department of Commerce Ener gy Information
Electric dampers are much more effect ive, since they are Center, Techniques, Tactics & Tips, Home Energy Guide to
timed to go on and off with the burner. They also have a Home Heating. Energy Information Center publications are
available free. They include Combustion Air, Home Energy
built-in safety feature that prevents the burner fro m lighting
Guide; Drafthood Test for Combustion Air, a check for
if the damper fails to open.
homeowners; and Furnace and Boiler Tune-Up, a checklist
All vent dampers must pass certain safety standards before American Council for an Energy -Efficient Economy
the City Building Code permits installation. If they are not (ACEEE) 6th edition, The Most Energy Efficient Appliances
up to standard, or are imp roperly installed, they can be 1995, available from bookstores for $8.95 or from 1001
extremely dangerous. If the damper doesn’t open when the Connecticut Avenue N.W. Suite 801, Washington, D.C.
burner comes on, co mbustion gases will bu ild up in the 20036, 202-429-0063 or www.aceee. org
Chi mney liners
An oversized chimney wastes
heat and drafts poorly. One
solution is to put in a correctly
sized metallic liner to reduce
airflo w. A liner also extends the
life of masonry chimneys by
preventing deterioration fro m the
flue gases. Liners must be
properly installed and tested by a
qualified service person to make
sure combustion gases do not
spill into the liv ing space. This is
especially impo rtant if you are
replacing your furnace but not
the combustion water heater; in
Residential Energy Assessment Program Heating Systems