Types of Furnaces
Gas is the most common fuel for hot air furnaces in the U.S. because natural gas is plentiful and relatively affordable compared to other fuel sources. Federal regulations require a minimum AFUE (annual fuel utilization efficiency; see below for more information) of 90 percent for furnace upgrades and new installations in 30 northern states in the U.S.; at least 80 percent elsewhere.
Although oil is less commonly used in the U.S., it's a necessity in places where natural gas is not an option -- and a preferred fuel for those who prefer to live more "off the grid." Upgrading to an oil furnace with an AFUE of at least 90 percent can cut CO2 emissions by 2.5 tons per year, as well as saving on energy costs.
Instead of heating air which is then distributed through the house via a duct system, boilers, also known as hydronic heating, heat water that is then transferred to radiators, baseboard heaters or radiant floor systems throughout the home. Boilers can powered by gas, oil, or electricity.
Although they're only appropriate for milder climates, heat pumps are a highly affordable, efficient method of heating. Heat pumps are powered by electricity and work by constantly transporting warm air from one place to another.
Radiant Floor Heating
With radiant floor heating systems, warm air rises from the floor, rather than circulating around the room. They're best for specific rooms or areas -- such as a chilly, tiled bathroom floor. In many cases, installing radiant floor heating is a job that a handy do-it-yourselfer can tackle.
Improving your furnace can save
people are locked in to their furnace type -- you buy a home, it has a gas,
oil, or electric-powered furnace, so that's what you live with. Replacing a
furnace is never an inexpensive proposition, and completely retrofitting a
system -- for example, replacing forced air with hydronic (hot water) heat can
be prohibitively expensive.
good news is that replacing an older furnace with a newer, more efficient
furnace can result in significant cost savings -- as well as being a positive
step for the environment. The federal government is keenly interested in the
effect on the environment of home heating systems and, as a result, as of May
1, 2013, federal regulations for non-weatherized furnaces of all types went
into effect that require a minimum annual fuel
utilization efficiency (AFUE) rating of 80 percent for gas furnaces, 83
percent for oil furnaces. On Jan. 1, 2015, additional regulations went into
effect for weatherized furnaces requiring a minimum AFUE of 81 percent for gas,
and 78 percent for oil. However, in 30 northern states, the standards
for gas furnaces are more stringent -- requiring a minimum AFUE of 90 percent. Weatherized
furnaces are generally installed outdoors and non-weatherized furnaces are
an ailing or old furnace might also get you a local tax credit or a rebate from
your utility company. For a complete, state-by-state list of credits and
rebates, visit the Database of State Incentives for Renewables & Efficiency (DSIRE) website.
keep in mind that, if you're using only one room of your house, or if one room
that you use a lot is particularly chilly, you might be able to warm up your
space without cranking up the heat. Space heaters or electric blankets, which we cover in their own reports, may help with that.
choose a furnace
Unless you are a near professional-level do-it-yourselfer, experts say
you must work with a reliable contractor and let that person's expertise guide
you in choosing a furnace. A skilled heating, ventilation and air conditioning (HVAC) contractor will evaluate your home's energy
needs and help you choose a furnace that is the right size and efficiency for
you, based on a number of factors.
few exceptions, furnaces and installation are sold as package deals along with
the installation. Any contractor you work with should offer you a choice of
furnace models with different efficiency ratings and should provide an estimate
of annual operating costs for each one. Most contractors specialize in working
with certain brands of furnaces, and some work with only one particular brand.
This can be an advantage, because it means the contractor has most likely
received specialized training from that manufacturer. However, it also means
that your furnace choices will be limited to that one brand. If you get an
estimate from a contractor who deals only in one brand, get estimates from
other contractors as well, making sure the furnaces they recommend are
equivalent in size and efficiency.
Another tip from experts is to steer clear of companies that offer to
give you an estimate over the phone. A reliable estimate must be based on a
thorough survey of your home. The contractor should consider such factors as
the size of the house, insulation levels, number and type of windows and the
climate in your area. He or she should inspect your ductwork (if any) for air
leaks and insulation level and measure airflow levels. The contractor should
also ask you about any problems you have had with your existing heating system.
Based on all this information, the contractor can perform a heat-load
calculation to determine the proper size of your new furnace.
A contractor should never base this decision on the size of your
existing furnace. Many homes have furnaces that are too large, partly because
sizing methods have improved and partly because buildings have become more
energy efficient. A furnace that is too large will not only cost more to
install and operate, but it may not heat your home as evenly as one that is
properly sized. A good contractor should evaluate your entire heating system
and make appropriate suggestions for improving the overall energy efficiency of
your home. This may allow you to purchase a smaller furnace and save money.
Contact several contractors and get an estimate in writing from each
one. Most sources recommend getting at least three estimates. If you already
know a reputable HVAC contractor, start your search with that person. Focus on
local companies, and look for contractors who are licensed and insured.
The written estimate you get from each contractor should spell out all
the details about the installation. It should describe the equipment to be
installed, the work to be done, the costs for materials and labor and the
payment schedule. It should also describe the equipment and installation
warranties and provide a firm date for completion of the project. Make sure
bids include all costs associated with the project, including permit fees (if
required). Compare all your estimates and make sure that they cover the same
work and the same type of equipment.
It may be tempting to go with the contractor who offers you the lowest
estimate, but experts warn that price is not the most important consideration.
For example, very low bids may not include routine services and customary
warranties. If one contractor's bid is dramatically different from the others,
don't hesitate to ask why. It's possible that this contractor has noticed
something that others missed -- or vice versa.
How we evaluated furnaces
publications or web sites conduct comparative reviews of furnaces or
comprehensively rate individual models, and it's easy to understand why. A
tester would have to install furnaces in identical homes to compare them. How
well a furnace functions depends on the installation of the whole system,
including ductwork and venting. Factors such as climate, home size, insulation,
window condition and usage will also affect performance. Even evaluating the
long-term reliability of a particular model is problematic because furnaces are
made to last 15 to 20 years, and technology can change a lot over such a long
However, there are a number of
helpful sources in detailing the types of furnaces available, new furnace
technology, and how to choose the right furnace for you home, as well as
discussions of whether or not a new furnace will be cost-effective. The U.S.
Department of Energy and the American Council for an Energy-Efficient Economy
(ACEEE), which maintains the website SmarterHouse.org, have a number of helpful
resources. ConsumerReports.org offers a free furnace buying guide, although it
covers only gas furnaces. In addition, we found sites directed at
do-it-yourselfers and home improvement topics, such as BobVila.com and
ThisOldHouse.com to be very helpful.