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Gas Furnace Replacement Considerations
There are several points to consider when choosing a replacement gas furnace. I will list them in
the order I believe they should be considered by their overall importance.
Proper Installation: This is the most important consideration and one the manufacturer
has very little control. They rely on their contractor/dealer to sell the right equipment for the job,
then install it following their instructions, and then test it to ensure it is operating within proper
operating parameters. All the equipment comes with a complete instruction manual that includes
all the mechanical and building codes that apply to that furnace.
When I worked for other contractors as a service technician I noticed that these manuals were
hardly ever referenced. I learned this after an installation had already been completed often
months prior and I was there doing a follow up service call. It was then I discovered many times
that if the installers had followed the instructions I wouldn’t have had to go out and try to fix the
deficiencies caused by their improper installation. By that time the fix would be costly and
difficult though and would have been much easier if it had been done right in the beginning.
ASHRAE (American Society of Heating Refrigeration and Air Conditioning Engineers) is our
national organization that is responsible for determining standards for HVAC equipment. They
conduct testing on equipment to find out the optimum requirements for airflow, temperature rise
and other essential engineering parameters. They conducted a study in 1997 of over 1200 recent
residential HVAC installations in Atlanta, Georgia, their home city and found that only 3 out of 10
were properly installed and of the remaining 7 installs, 4 out of 10 were seriously deficient in
proper airflow and/or freon charge and would probably would experience a major failure such as
compressor lockup or heat exchanger cracking within a year. These installations were not being
done by fly-by-night unlicensed operators or small mom and pop operations but most of them
were being done by the larger well advertised and well respected companies in their community.
There are many procedures in the installation that require proper compliance and attention to
detail. Before the install even starts, when the salesman/estimator comes out and evaluates the
existing or new system, a properly sized duct system is essential. There is a duct design method
developed by both ASHRAE and ACCA (Air Conditioning Contractors of America) that should be
followed when sizing and installing duct systems. This duct sizing method is referred to as
Manual D. The size of the ducts, the type of fittings used, and the position of the duct runs all
contribute to a proper duct system.
When examining a preexisting blueprint with a duct layout already drawn or designing a new duct
system from scratch it is very important to ensure the duct system is designed to correctly deliver
the proper airflow. In the case of an existing drawing from an architect, don’t assume the architect
knows what he/she is doing in duct design. If there are design flaws, this is the time to point that
out before the design flaw actually gets built
When replacing equipment, recognizing existing ductwork that is undersized is essential . If
inadequate ductwork is discovered, that should be brought up. Then the replacement proposal
should include upgrades to the duct system to bring it to proper size for the airflow it must
deliver. Most of the time, the return air duct is undersized. An undersized return duct will act on
a furnace or air handler like a person who has asthma and it will be ‘gasping’ for air it cannot get.
The furnace will be overly noisy and might even whistle. If the return air duct is so restricted, the
HVAC equipment will suffer from inadequate airflow which will cause liquid freon flood-back to the
compressor in the summer and over heating and subsequent cracking of the heat exchanger in
the winter. In addition to these consequences to the equipment the house will also suffer with
inadequate cooling and heating especially in rooms which are furthest from the furnace.
Here are other considerations. Proper venting of gas furnaces is of the utmost importance to the
safety of customer as well as impacting the operation of the equipment. Ensuring adequate
combustion air is a must especially in closet installations. Proper sizing of gas piping and proper
sealing of all the fittings of the gas pipe system prevents gas leaks and possible fire or
explosions. Having the correct size electrical power to the equipment ensures safe operation of
the equipment. Proper selection and placement of the thermostat controls, guarantees optimum
temperature control. All of these items are outlined with detail in the installation manual which is
often discarded or ignored by many in this industry.
Most residential HVAC companies pay their installers and service techs very little compared to
the knowledge and responsibility they must display. The average installer makes between $8 to
12 dollars per hour with the top end guy maybe getting $15. Service techs make a little more than
installers, about 10 to 15% more. This is hardly the pay that is deserved by someone who impacts
both your safety and comfort of your family. With the amount of knowledge that is required of
technicians they should be getting a minimum of $20/hour.
I know this first hand for I put in many years in this industry as a service tech, a salesman, as an
instructor at both ITT and Ivy Tech, and now as a HVAC contractor. In the summer of 1998 when I
was teaching I had to work for local contractor because I didn’t receive a full contract at Ivy Tech
State College for lack of enrollment. They paid me $12/hr and they told me this was the highest
hourly pay they had in the company. They had even given me an extra $1/hr. because they didn’t
have to provide me with health insurance since Ivy’s health plan covered me over the summer.
They cautioned me not to tell a soul about my pay. This wasn't a small HVAC company but one of
the largest in replacement furnaces and a/c units at least in terms of the number of permits they
pull every year. Even though this happened 13 years ago the pay situation hasn’t substantially
changed.
The salesman/estimator is more than likely to be untrained in recognizing poor ductwork, but
much more skilled in selling you more expensive equipment and increasing their commissions. In
addition to missing duct problems they also are notorious for over sizing the system just so they
can get a few more dollars out of the job. Oversized equipment with undersized ductwork, is a
formula for disaster. The results are systems that never work right from the beginning with
unnecessary failures and unsatisfactory performance. This is especially true in new construction
where the low bid gets the job and every corner that can be cut is cut resulting in duct systems
and units which have chronic problems. I don’t understand why builders put such bottom-of-the-
line equipment in their houses. I’m not talking cheap houses either…it’s the same even in the
best homes. I do a fairly good business rectifying mistakes made at the beginning with the
construction of the house.
Reliability: You can go to websites such as www.furnacecompare.com and other sites such as
Consumer Reports to get other opinions on the reliability of furnaces and other hvac equipment.
For the most part these sites are anecdotal and report only on the customer’s overall experience
of a furnace. In many cases the problems reported with furnaces or brands are a reflection of
poor job in installation or an improper equipment selection process. In those cases they are not
complaining so much about the equipment as the expertise of the contractor.
I sell Carrier www.residential.carrier.com equipment. I choose Carrier because they are the #1
manufacturer in the USA in terms of market share, 18% according to the Air Conditioning and
Heating Contractors Magazine. I believe that when you do a lot of something you get good at it.
When I sell a product I stand behind it and I place my reputation on the line. Selling equipment
which breaks down or has parts that are hard to get is a sure fire way to make my customers
unhappy. My business depends on my customers pleasure and comfort. So I sell products that I
am confident in so as to pass that along. My best advertising is word of mouth. A happy
customers will tell ten friends. An unhappy one will tell hundreds.
I like Carrier because they use a heavier grade sheet metal in their cabinets. This makes them
heavier, stronger, and less susceptible to stray noise or vibration which in turn make them less
likely to break down. In addition their research department does extensive testing of their
products in a variety of harsh conditions inside environmental chambers. When I was an HVAC
instructor at Ivy Tech State College I brought my students out to their factory on the Westside of
Indy to see how the equipment is made and tested. I was very impressed with their diligence to
quality and their commitment to excellence. They test fired all the equipment that rolled off the
assembly line to make sure it would run. If a piece didn’t work the first time they would roll it off
the line and then repair it but they would only sell it as a ‘factory second or rebuild’ to their non
authorized dealer distributors.
Efficiency or Cost of Fuel: Higher efficient equipment is more expensive initially than standard
efficient both from contractor cost and the extra installation required on a PVC flue system. Right
now the standard efficient furnace needs to be a minimum 80% though that will change in 2015 for
northern states to 90%. Higher efficiency is done by condensing the water vapor present as a by
product of combustion removing that heat from the flue gas. In addition efficiency is improved by
using an on demand system for lighting the gas, by the use of two stage gas valves, by
implementing modulating controls of both the inducer fan motor and the main blower motor and
by designing the heat exchanger so that there is more thorough contact and transfer of the hot
combustion gas to the fresh building air.
Efficiency of up to 97% is available though Carrier will have available a furnace which is 98% in this
year 2013. Most old furnaces are between 70 and 80% efficient with some of the old “lunkers”
(pre 70’s) being about 50 to 60%. High efficiency furnaces start at about 90 to 92% on the low end,
a 93 to 95% in mid dollar range and then go to 95 to 96% on the high end. I recommend a variable
drive blower whichever efficiency you go with for its’ ability to deliver better cooling airflow to
upstairs rooms in the summer.
If you go from an 70%er to a 95% that is an increase of 25% that should translate into a 25%
reduction in your annual heating bill. For the average size modern house of about 2200 square
feet that should save between $250 to $350 annually. Since a furnace should last about 20 years
this is a lifetime savings of $5000 to $7000. This amount would well the recuperate the extra cost
of the more expensive furnace which might add an extra $1500 to 2000 at the time of installation.
This does take into account the positive environmental impact of the smaller carbon footprint of
the more efficient furnaces, and the improved effect on our planet of less wasted energy, and the
reduction in emission of CO2 which increases the risk for global warming.
There are additional incentives available for upgrading the efficiency of your furnace. Most
utility companies offer a $200 rebate for upgrading to higher efficiency equipment.
To go to an even higher efficiency and more savings I would recommend either a furnace/heat
pump combination called a hybrid or dual fuel system. See my page on heat pumps for more
details.
Ease of Repair: When it comes time to repair equipment it is important that parts are
easily accessible, that the system is easily understood, and that it even has a built in self
troubleshooting system. All the furnaces I sell of Carrier have all of these essential properties.
Carrier especially goes out of their way to provide low cost training for the technician. They have
easy to read service manuals and their
Availability and Cost of Parts: Because of their popularity the parts for Carrier are easily
attained. Carrier is made right here in Indianapolis at their factory out by the airport. There are
three locations of distributors that handle Carrier parts in Indianapolis: two Habeggers, and
Koch. In addition to these authorized distributors a lot of the parts can also purchased from
aftermarket replacement distributors who offer generic replacement parts for most of the
common parts in Carrier. In addition to the above parts suppliers there are on-line parts vendors
who sell a lot of the common parts.
There are several points to consider when choosing a replacement gas furnace. I will list them in
the order I believe they should be considered by their overall importance.
Proper Installation: This is the most important consideration and one the manufacturer
has very little control. They rely on their contractor/dealer to sell the right equipment for the job,
then install it following their instructions, and then test it to ensure it is operating within proper
operating parameters. All the equipment comes with a complete instruction manual that includes
all the mechanical and building codes that apply to that furnace.
When I worked for other contractors as a service technician I noticed that these manuals were
hardly ever referenced. I learned this after an installation had already been completed often
months prior and I was there doing a follow up service call. It was then I discovered many times
that if the installers had followed the instructions I wouldn’t have had to go out and try to fix the
deficiencies caused by their improper installation. By that time the fix would be costly and
difficult though and would have been much easier if it had been done right in the beginning.
ASHRAE (American Society of Heating Refrigeration and Air Conditioning Engineers) is our
national organization that is responsible for determining standards for HVAC equipment. They
conduct testing on equipment to find out the optimum requirements for airflow, temperature rise
and other essential engineering parameters. They conducted a study in 1997 of over 1200 recent
residential HVAC installations in Atlanta, Georgia, their home city and found that only 3 out of 10
were properly installed and of the remaining 7 installs, 4 out of 10 were seriously deficient in
proper airflow and/or freon charge and would probably would experience a major failure such as
compressor lockup or heat exchanger cracking within a year. These installations were not being
done by fly-by-night unlicensed operators or small mom and pop operations but most of them
were being done by the larger well advertised and well respected companies in their community.
There are many procedures in the installation that require proper compliance and attention to
detail. Before the install even starts, when the salesman/estimator comes out and evaluates the
existing or new system, a properly sized duct system is essential. There is a duct design method
developed by both ASHRAE and ACCA (Air Conditioning Contractors of America) that should be
followed when sizing and installing duct systems. This duct sizing method is referred to as
Manual D. The size of the ducts, the type of fittings used, and the position of the duct runs all
contribute to a proper duct system.
When examining a preexisting blueprint with a duct layout already drawn or designing a new duct
system from scratch it is very important to ensure the duct system is designed to correctly deliver
the proper airflow. In the case of an existing drawing from an architect, don’t assume the architect
knows what he/she is doing in duct design. If there are design flaws, this is the time to point that
out before the design flaw actually gets built
When replacing equipment, recognizing existing ductwork that is undersized is essential . If
inadequate ductwork is discovered, that should be brought up. Then the replacement proposal
should include upgrades to the duct system to bring it to proper size for the airflow it must
deliver. Most of the time, the return air duct is undersized. An undersized return duct will act on
a furnace or air handler like a person who has asthma and it will be ‘gasping’ for air it cannot get.
The furnace will be overly noisy and might even whistle. If the return air duct is so restricted, the
HVAC equipment will suffer from inadequate airflow which will cause liquid freon flood-back to the
compressor in the summer and over heating and subsequent cracking of the heat exchanger in
the winter. In addition to these consequences to the equipment the house will also suffer with
inadequate cooling and heating especially in rooms which are furthest from the furnace.
Here are other considerations. Proper venting of gas furnaces is of the utmost importance to the
safety of customer as well as impacting the operation of the equipment. Ensuring adequate
combustion air is a must especially in closet installations. Proper sizing of gas piping and proper
sealing of all the fittings of the gas pipe system prevents gas leaks and possible fire or
explosions. Having the correct size electrical power to the equipment ensures safe operation of
the equipment. Proper selection and placement of the thermostat controls, guarantees optimum
temperature control. All of these items are outlined with detail in the installation manual which is
often discarded or ignored by many in this industry.
Most residential HVAC companies pay their installers and service techs very little compared to
the knowledge and responsibility they must display. The average installer makes between $8 to
12 dollars per hour with the top end guy maybe getting $15. Service techs make a little more than
installers, about 10 to 15% more. This is hardly the pay that is deserved by someone who impacts
both your safety and comfort of your family. With the amount of knowledge that is required of
technicians they should be getting a minimum of $20/hour.
I know this first hand for I put in many years in this industry as a service tech, a salesman, as an
instructor at both ITT and Ivy Tech, and now as a HVAC contractor. In the summer of 1998 when I
was teaching I had to work for local contractor because I didn’t receive a full contract at Ivy Tech
State College for lack of enrollment. They paid me $12/hr and they told me this was the highest
hourly pay they had in the company. They had even given me an extra $1/hr. because they didn’t
have to provide me with health insurance since Ivy’s health plan covered me over the summer.
They cautioned me not to tell a soul about my pay. This wasn't a small HVAC company but one of
the largest in replacement furnaces and a/c units at least in terms of the number of permits they
pull every year. Even though this happened 13 years ago the pay situation hasn’t substantially
changed.
The salesman/estimator is more than likely to be untrained in recognizing poor ductwork, but
much more skilled in selling you more expensive equipment and increasing their commissions. In
addition to missing duct problems they also are notorious for over sizing the system just so they
can get a few more dollars out of the job. Oversized equipment with undersized ductwork, is a
formula for disaster. The results are systems that never work right from the beginning with
unnecessary failures and unsatisfactory performance. This is especially true in new construction
where the low bid gets the job and every corner that can be cut is cut resulting in duct systems
and units which have chronic problems. I don’t understand why builders put such bottom-of-the-
line equipment in their houses. I’m not talking cheap houses either…it’s the same even in the
best homes. I do a fairly good business rectifying mistakes made at the beginning with the
construction of the house.
Reliability: You can go to websites such as www.furnacecompare.com and other sites such as
Consumer Reports to get other opinions on the reliability of furnaces and other hvac equipment.
For the most part these sites are anecdotal and report only on the customer’s overall experience
of a furnace. In many cases the problems reported with furnaces or brands are a reflection of
poor job in installation or an improper equipment selection process. In those cases they are not
complaining so much about the equipment as the expertise of the contractor.
I sell Carrier www.residential.carrier.com equipment. I choose Carrier because they are the #1
manufacturer in the USA in terms of market share, 18% according to the Air Conditioning and
Heating Contractors Magazine. I believe that when you do a lot of something you get good at it.
When I sell a product I stand behind it and I place my reputation on the line. Selling equipment
which breaks down or has parts that are hard to get is a sure fire way to make my customers
unhappy. My business depends on my customers pleasure and comfort. So I sell products that I
am confident in so as to pass that along. My best advertising is word of mouth. A happy
customers will tell ten friends. An unhappy one will tell hundreds.
I like Carrier because they use a heavier grade sheet metal in their cabinets. This makes them
heavier, stronger, and less susceptible to stray noise or vibration which in turn make them less
likely to break down. In addition their research department does extensive testing of their
products in a variety of harsh conditions inside environmental chambers. When I was an HVAC
instructor at Ivy Tech State College I brought my students out to their factory on the Westside of
Indy to see how the equipment is made and tested. I was very impressed with their diligence to
quality and their commitment to excellence. They test fired all the equipment that rolled off the
assembly line to make sure it would run. If a piece didn’t work the first time they would roll it off
the line and then repair it but they would only sell it as a ‘factory second or rebuild’ to their non
authorized dealer distributors.
Efficiency or Cost of Fuel: Higher efficient equipment is more expensive initially than standard
efficient both from contractor cost and the extra installation required on a PVC flue system. Right
now the standard efficient furnace needs to be a minimum 80% though that will change in 2015 for
northern states to 90%. Higher efficiency is done by condensing the water vapor present as a by
product of combustion removing that heat from the flue gas. In addition efficiency is improved by
using an on demand system for lighting the gas, by the use of two stage gas valves, by
implementing modulating controls of both the inducer fan motor and the main blower motor and
by designing the heat exchanger so that there is more thorough contact and transfer of the hot
combustion gas to the fresh building air.
Efficiency of up to 97% is available though Carrier will have available a furnace which is 98% in this
year 2013. Most old furnaces are between 70 and 80% efficient with some of the old “lunkers”
(pre 70’s) being about 50 to 60%. High efficiency furnaces start at about 90 to 92% on the low end,
a 93 to 95% in mid dollar range and then go to 95 to 96% on the high end. I recommend a variable
drive blower whichever efficiency you go with for its’ ability to deliver better cooling airflow to
upstairs rooms in the summer.
If you go from an 70%er to a 95% that is an increase of 25% that should translate into a 25%
reduction in your annual heating bill. For the average size modern house of about 2200 square
feet that should save between $250 to $350 annually. Since a furnace should last about 20 years
this is a lifetime savings of $5000 to $7000. This amount would well the recuperate the extra cost
of the more expensive furnace which might add an extra $1500 to 2000 at the time of installation.
This does take into account the positive environmental impact of the smaller carbon footprint of
the more efficient furnaces, and the improved effect on our planet of less wasted energy, and the
reduction in emission of CO2 which increases the risk for global warming.
There are additional incentives available for upgrading the efficiency of your furnace. Most
utility companies offer a $200 rebate for upgrading to higher efficiency equipment.
To go to an even higher efficiency and more savings I would recommend either a furnace/heat
pump combination called a hybrid or dual fuel system. See my page on heat pumps for more
details.
Ease of Repair: When it comes time to repair equipment it is important that parts are
easily accessible, that the system is easily understood, and that it even has a built in self
troubleshooting system. All the furnaces I sell of Carrier have all of these essential properties.
Carrier especially goes out of their way to provide low cost training for the technician. They have
easy to read service manuals and their
Availability and Cost of Parts: Because of their popularity the parts for Carrier are easily
attained. Carrier is made right here in Indianapolis at their factory out by the airport. There are
three locations of distributors that handle Carrier parts in Indianapolis: two Habeggers, and
Koch. In addition to these authorized distributors a lot of the parts can also purchased from
aftermarket replacement distributors who offer generic replacement parts for most of the
common parts in Carrier. In addition to the above parts suppliers there are on-line parts vendors
who sell a lot of the common parts.
| CLICK HERE FOR A PRODUCT COMPARISON OF BRYANT GAS FURNACES: http://www.bryant.com |
| CLICK HERE FOR A PRODUCT COMPARISON OF GOODMAN GAS FURNACES: http://www.goodmanmfg.com |