Gas Furnaces ---- Frequently Asked Questions:
1. What is "AFUE"?
The Annual Fuel Utilization Efficiency. In a general sense, it is a measure of
the amount of heat that you actually get inside of the home compared to the
amount of heat that is being used by the system. As an example, a 100,000 BTU,
80% AFUE gas furnace will provide 80,000 BTU's of heat into the home if it runs
for one hour. The other 20,000 BTU's of heat will go up the chimney as products
of combustion.
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2. How important is AFUE?
The least efficient gas furnace available today has a AFUE of 78%. All furnace
manufacturers today build two efficiency ranges of gas furnaces. Their standard
gas furnace will be between 78%-81% efficient (called "80% AFUE") and their
high efficiency gas furnace will be between 90%-96% efficient (called "90%
AFUE). To be practical, most homes will have some factor that will justify one
efficiency range or the other. In very few homes are both efficiency ranges
equally practical.
The 80% AFUE gas furnaces require some type of masonry or metal vertical
chimney. A home with an existing chimney is usually a candidate for the 80%
AFUE furnace. A home that currently has no chimney (ie, existing heat pump home
that may be switching to natural gas) or a home that has a very old defective
chimney, probably would be the best candidate for a 90% AFUE gas furnace. Other
factors also play into the choice.
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3. What air conditioner works best with a gas
furnace?
Any efficiency air conditioner (or heat pump) will operate with a gas
furnace. There is no one type or efficiency
that is "better". In most
parts of the country the heating system
runs more than the air conditioner and
is, therefore, the more expensive item
to operate. For this reason, We recommend
that your choice of a furnace is more important
than the air conditioner. You
will benefit from purchasing the best,
lowest operating cost, gas furnace. If this
stretches the budget, then purchase the
more standard model air conditioner.
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4. Do all 12 SEER air conditioners perform the same?
When comparing different brands of air conditioners, a 12 SEER 3 ton brand "A"
will offer the same COOLING operating costs as a 12 SEER 3 ton brand
"B". However, one brand may do a better job of removing moisture from
the air. The better the moisture removal, the more comfortable you
will be-even at a
warmer temperature. An air conditioner
that is over-sized (too large) will cool a home very quickly but, due
to the shorter "run" time, it will not remove as much moisture. A slightly
undersized air conditioner that must run more often will actually provide
a more comfortable
home, better humidity control, and at
a lower operating cost.
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5. What is a "ton" of air conditioning?
One ton of air conditioning is 12,000 BTU. A BTU is short for British thermal
unit and is the amount of heat that will raise or lower one pound of water by
one degree Fahrenheit. It is important to note that actual capacity is not
constant and will change based on outdoor or indoor temperature. The published
rating of a unit is based upon capacity when the outdoor temperature is 95
degrees F. and the inside temperature is 80 degrees F.
Also, some manufacturers may call their unit a 3 ton system even though it only
delivers 34,000 BTU. Another manufacturer may be offering 37,000 BTU's with
their 3 ton unit.
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6. How often should filters be cleaned or
replaced?
Filters should be replaced/cleaned once per month. Many "high efficiency" air
filters have a longer useful life. All of the electronic & electrostatic
filters must be cleaned a minimum of once per month. Allowing a filter
to become clogged with dirt will raise the operating costs of the system and
can actually cause damage to the compressor.
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7. Should a thermostat be set to "auto" or "on"?
When the thermostat is set to "auto", the fan operates only when the temperature
requires it (whenever the cooling unit or heating unit is running). When set to
"on", the fan operates all the time. You may want the fan to run all the time
to do its best possible job of filtering the air.
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8. What is my "best buy" in a gas furnace?
This question will have a different answer based upon the needs of the
purchaser. The choice between 80% AFUE and 90% AFUE is usually made based upon
the home itself. Once this choice is made, there are still several differences
in the gas furnaces offered in each efficiency range. For example, American
Standard offers 3 different types of 80% AFUE furnaces. The top of the line
furnace will provide lower operating costs than the standard model and will be
quieter and more comfortable.
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9. I've heard a lot about new refrigerants. What
are the facts?
Residential heat pumps and air conditioners contain a refrigerant called R-22
which is classified as an HCFC. This is an environmentally safe and efficient
refrigerant that will be available as long as your new system will last. There
are some rulings being made by the US Environmental Protection Agency which
require changes be made to refrigerants but not until the year 2020.
Manufacturers will be producing units using R-22 until the year 2010 and the
refrigerant itself will be available until 2030.
Manufacturers are testing many new refrigerants (and have been doing so for over
10 years). There are currently two frontrunners as possible replacements for
R-22. One is called R-134 and the other is R-410A. One manufacturer who markets
equipment under three different names has chosen to offer R-410A refrigerant in
some units and they have given this refrigerant a "name"-Puron. No other
manufacturer has taken a chance with this refrigerant because it operates at
higher pressures than R-22. In fact it takes special equipment to work with
Puron because of the higher pressures.
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10. What is the difference in a Manufacturer's
Limited Warranty and an Extended parts and labor Warranty?
A limited warranty covers specific parts (i.e. compressor, coil, electronics,
etc.); therefore, it is limited by the language in the warranty. Extended
warranties are generally purchased in addition to the equipment. Extended
warranties cover all parts and may also include the labor for the service call.
An extended warranty protects you for unexpected and unbudgeted service calls
for the duration of the warranty. Be aware that no warranty includes
maintenance, shipping costs, and related parts (parts not provided by the
manufacturer). Most labor warranties do not include labor for diagnostics. Most
of the better manufacturer's now require proof that routine maintenance has
been performed on the equipment. If a contractor offers a labor or long parts
warranty, you should remember that it is only good as long as the dealer is in
business.
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11. What size system do I need for my home?
There are many things which will determine the size (capacity) system your home
requires. Some of these are: square feet to be heated, local climate, humidity,
number of windows, size of windows, type of windows, insulation factors,
direction your home faces, heat producing appliances, and even the number of
people who will be in the home. There are several different types of analysis
that will help determine the proper unit. Contractors may tend to offer you a
gas furnace that is too large for a home. Some do this because they do not know
any better. Others do this because they assume that the homeowner thinks
"bigger is better". You see, there is very little difference in "cost" between
one size furnace and another. Yet a homeowner may be fooled into thinking that
he is getting a better buy because the furnace is larger.
I have seen contractors quote a gas furnace (to replace a heat pump) that is
twice the capacity of the old heat pump. The most efficient gas furnace is a
unit that is the correct size, not one that is too big!
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12. How do I find a dealer who will do a good job?
The same rules apply here as for any contractor. Ask people you know who have
had an air conditioning system installed and if they would recommend them.
Check with the Better Business Bureau. Use a company that has an established
business and had technicians "on call". Remember that, even a new system, will
break down sometime. It will probably be on a holiday or weekend. The
"moonlighter" or "one man shop" probably will be out of town or even out of
business.
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13. What is the difference
between manufacturers products?
First, you are probably aware that most manufacturers market their gas furnaces
under several different brand names. Often these furnaces are identical.
Carrier markets under several brand names including Bryant. Rheem markets under
the name Ruud. American Standard markets under their own name plus Trane. The
list goes on and on. The differences between truly competing gas furnaces can
be significant. The thickness of the metal used for the equipment jacket
(quietness), the thickness of the heat exchanger (quality), the construction of
the inner parts of the furnace (quietness), quality of the internal components,
warranty, insulation, packaging, availability of parts-all are areas where a
gas furnace can be made into a quality product or just a commodity.
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14. My gas furnace is no longer heating
properly. What is the most likely problem?
Most of our "replacement" gas furnaces are sold because the old furnace
developed a crack in the heat exchanger. The crack is seldom visible to the
untrained eye. Sometimes it is not visible to the most experienced technician
but he is able to make a judgement call based upon the operation of the system.
Maybe the pilot light keeps going out. Maybe a safety switch sometimes cuts the
furnace off. Then the homeowner resets the furnace and it seems to work for a
few days. Both of the above could be due to a cracked heat exchanger. As the
"crack" gets larger, the chance that the furnace will malfunction becomes much
greater. If the homeowner fails to see the symptoms, eventually a technician
will be called for repairs.
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15. What is a cracked heat exchanger?
The heat exchanger is the area of the furnace where "heat" is exchanged-from the
fire at the gas burner to the air that is recycled into the home through the
duct system. The heat exchanger is sealed so that the products of combustion
from the gas burner never come into contact with the air that goes back into
the home. When a "crack" develops, the seal between the two sides has broken
and the products of combustion (including carbon monoxide) can mix with the air
going into the home.
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16. When do I know it's time to replace my
system?
When the system starts giving more problems than seem cost-effective to fix,
particularly when major components such as the gas valve or heat exchanger
fail. When faced with major repairs, consider that a new system will eliminate
costly repairs and will save money on your monthly power bill because of the
increased efficiency. The average life of a gas furnace is 18-20 years. We
recommend that any gas furnace over 12 years old only be repaired as a last
resort. The newer models are so much more efficient that often they will help
pay for themselves with the fuel they save.
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17. Should I keep running my old system
until it wears out or replace it sooner?
Because newer equipment usually is more energy efficient than older central air
conditioning or heat pump systems, you may actually save money by replacing
your old system before it wears out. In some cases, the money you save in
reduced utility costs might pay back your purchase price of a new system years
earlier than you might think.
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18. What is the best type of system to meet
all indoor comfort needs?
The best system depends on many variables, including family size, house
location, design, and utility costs. The optimum indoor comfort system might
include high efficiency air conditioning, high efficiency heating, high
efficiency air cleaning, air purification, and humidification.
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19. Should I install a heat pump instead of a
regular air conditioner if I have a gas or oil heating system?
A heat pump can be a worthwhile consideration no matter what heating system is
used in a home. In many areas, a heat pump with gas or oil supplementary heat
is the most economical system.
The above paragraph is the "text" answer nationally. Our answer
is based upon local weather conditions,
prices for local fuels, and past
feedback from customers. The above answer
is technically correct for the most economical
system. However, the gas furnace/heat pump
combination system will
normally cost about $600-$800 more than
gas furnace/air conditioning. We recommend
that you spend the extra money for a deluxe
gas/air conditioning system such as a "two-stage" gas furnace or
a "variable speed" gas
furnace.
For the oil furnace/heat pump combination system you will normally
spend about $600-$800 more than for a
oil furnace/air conditioner. This is well spent money
if the home is fairly well insulated.
If not well insulated, We would recommend
that the extra money be spent on insulation.
A very few energy conscious customers have used these "dual fuel" heating
systems for many years. Most of our customers, within a few years after
purchasing the "dual fuel" systems, have turned off the "dual" capability and
now heat with their gas or oil furnace. The reason given by these customers is
usually that the difference in air temperature (between the heat pump heated
air and the gas furnace heated air) is great enough that they are not
comfortable during times when the system switches from one fuel to the other.
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20. What about having my ducts cleaned?
Duct outlets and registers should be cleaned as part of your regular home
cleaning routine. It's the filter in the system, and to a lesser degree the
grilles and registers at the duct outlets, that collect most of the dust, and
therefore need changing or cleaning.
Ducts usually don't require cleaning, especially if filters are kept clean, You
can occasionally check ducts by removing a few registers and inspecting the
ducts from the inside with a flashlight. I have never seen a heat pump duct
system that needed cleaning. I have never seen a properly operating gas or oil
furnace duct system that needed cleaning. I have only seldom seen a gas furnace
duct system that could have benefitted from cleaning, and never a system less
than 30 years old. Many oil furnace duct systems could benefit from cleaning if
the oil furnace has ever "cracked", malfunctioned, or been in use over 30
years.
Some contracting companies have invested in special "duct cleaning" equipment
and often offer specials just to keep their cleaning crew busy. Of course, you
can find dust inside of your ducts but your money might be better spent on
purchasing a high efficiency air filter-that would keep the ducts super clean
in the future.
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21. Should my home be humidified?
That depends largely on your personal needs. Humidification is definitely
helpful in many homes during a 6-8 week period during the coldest winter
weather. In the coldest weather insufficient moisture in the air often is
responsible for such assorted problems as stuffy noses, sore throats, more dust
than usual, cracks and dried-out joints in wood furniture, and static
electricity. A good humidifier can cost $350-$600.00. It will be used only
during the winter months and you will need to "clean and start" the humidifier
in the fall. When spring arrives, you must "drain, clean, and shut-down" the
humidifier or it could become a breeding ground for mold during the summer.
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