Furnace replacement in Oxford, Southbury and Naugatuck
How long does a furnace last in Connecticut?
A furnace in Connecticut usually lasts 15 to 20 years. Carrier and Bryant both publish that range for a gas furnace that gets regular maintenance, Carrier gives an oil furnace the same 15 to 20, and the U.S. Department of Energy’s own estimate for a gas furnace in the North is 22.5 years. A few reach 30. Most don’t, and the reason is rarely the furnace itself.
This page gives you the published ranges with their sources, where gas and oil differ, the four things that shorten a furnace’s life, the signs one is near the end, and how age, repair history and efficiency add up to a furnace replacement call in Oxford, Southbury or Naugatuck. If you already know the furnace is on its last legs, two of our other posts cover the decision and the money. This one is about age.
Takeaways
- A well-maintained gas furnace typically lasts 15 to 20 years, and a high-quality one can reach 30 with proper installation and consistent maintenance (Carrier).
- The U.S. Department of Energy estimates the average gas furnace lasts 21.5 years nationally and 22.5 years in the North, with published studies between 16 and 23.6 years (DOE furnace standards rule).
- An oil furnace carries the same 15 to 20 year range, and Carrier says oil furnaces typically need more frequent maintenance to prevent soot buildup (Carrier oil furnace guide).
- Manufacturers warrant the heat exchanger for 20 years to lifetime and the rest of the parts for 10 (Carrier, Bryant, Lennox). The gap between those two numbers is the whole lifespan question. Call 203-756-5040 to have yours dated.
What the published ranges say
Every range below comes from a page we opened, and they agree more than you’d expect. The manufacturers describe a furnace that is maintained the way the manual says. The Department of Energy counted how long furnaces actually stayed in service. It used appliance-age surveys and historical shipment records to estimate what it calls a survival function. Read the two side by side and you have the planning point and the average exit in the same table.
| Source | Furnace | Published range | What the source adds |
|---|---|---|---|
| Carrier, furnace lifespan guide | Gas | 15 to 20 years; “up to 30 years” for a high-quality furnace with proper installation and maintenance | “When your furnace reaches the 15-year mark, it is wise to begin researching furnace replacement options.” |
| Bryant, furnace lifespan guide | Gas | 15 to 20 years; “approximately 20 years” when well maintained, some beyond 20 | “Age alone does not determine when replacement is necessary.” Start budgeting around the 12 to 15 year mark. |
| Carrier, oil furnace guide | Oil | 15 to 20 years; high-quality models “can sometimes last up to 30 years” | Oil furnaces “typically require more frequent maintenance to prevent soot buildup.” |
| Carrier, furnace lifespan guide | Electric | 20 to 30 years | Rare in our towns; listed for completeness. |
| U.S. DOE, 2023 furnace standards rule | Gas (non-weatherized) | Average 21.5 years nationally; 22.5 years in the North, 20.2 in the rest of the country | Its literature review found average values between 16 and 23.6 years. |
| U.S. DOE, Energy Saver guide | Furnace or boiler | “Consider replacing” when it is more than 15 years old | Also when it “needs frequent repairs and your energy bills are going up,” or some rooms run too hot or too cold. |
What the warranties promise
A warranty is the number a manufacturer will put money behind, so it belongs next to the lifespan claim. On Carrier’s Infinity 98 gas furnace, timely registration buys a lifetime heat exchanger limited warranty (20 years if it is not registered within 90 days) and a choice of a 10-year parts limited warranty or 5 years of parts plus 3 years of labor. Carrier’s Comfort 80, an 80 percent AFUE furnace still in the catalog, carries a 20-year heat exchanger limited warranty. Bryant’s Evolution 96 reads the same way, lifetime on the heat exchanger with registration and 10 years on parts. Lennox’s SLP99V product page says its Dave Lennox Signature Collection models “come with a 10-Year Limited Warranty on covered components,” and that “furnace heat exchangers offer either 20-Year or Lifetime Limited Warranties.”
Read those together and the lifespan question fits in two numbers. The heat exchanger, the steel the flame heats, is warranted for 20 years or for life. Everything that moves or sparks around it, the blower motor, the igniter, the inducer, the control board, is warranted for 10. In our experience the furnace that leaves a basement at 16 or 18 rarely goes because its heat exchanger failed. It goes because the parts around the exchanger have already been replaced once, and a second round is not worth the money on a unit that age.
Gas versus oil furnaces
The fuel changes the maintenance, not the published range. Carrier’s oil furnace guide puts a well-maintained oil furnace at 15 to 20 years and says high-quality models can sometimes last up to 30, the same numbers it gives a gas furnace. The same page says why oil asks for more attention. Oil furnaces “typically require more frequent maintenance to prevent soot buildup,” and Carrier notes they remain common “in parts of the Northeast” where gas service is not on the street. We service plenty of oil furnaces on streets in Oxford and Southbury that have no gas main.
Oil also tops out lower on efficiency. Carrier’s current oil furnaces reach up to 87.5 percent AFUE, its gas furnaces up to 98.5. ENERGY STAR draws its line at 87 percent AFUE for an oil furnace and 97 percent for a gas furnace sold in the U.S. North, and its North list includes Connecticut. ENERGY STAR’s own furnace page says a certified northern gas furnace is up to 18 percent more efficient than a baseline model and “can save $160 a year,” while a certified oil furnace is up to 4 percent more efficient and saves “about $90.” Those are ENERGY STAR’s national estimates, not a Connecticut bill.
The American Heating position on oil furnaces
We install and service both fuels, and we do not push an oil customer toward gas on age alone. An oil furnace that gets its burner cleaned and its nozzle and filter changed every year ages the way a gas furnace does. The one that skips its cleanings is the one that soots its heat exchanger early. If gas is on your street and the furnace is past 15, the conversion belongs in the same conversation, and our oil-to-gas conversion page covers what that involves.
What shortens a furnace’s life
Carrier names four variables, size, installation quality, maintenance habits and usage. Bryant names maintenance, sizing, usage intensity and component quality. Here they are the way we meet them in Oxford, Southbury and Naugatuck basements, each with the manufacturer’s own words.
Skipped maintenance
Carrier says neglect lets dirty buildup accumulate on “heat exchangers, burners, and fan blades,” and that a dirty heat exchanger transfers heat less efficiently and runs longer. Bryant asks for a monthly filter check and annual professional service. The Department of Energy’s consumer heating guide says a regular maintenance schedule “will prolong the life of the equipment” and that furnaces “should be checked in the fall.” What a fall visit covers, and what it costs here, is in our fall tune-up guide.
Oversizing
A furnace that is too big for the house heats it fast and shuts off, then does it again. Carrier says those “shorter cycles place excessive stress on components, which can contribute to increased wear and premature failure,” and Bryant says the short cycling wears “the blower motor and heat exchanger.” The fix is upstream of the furnace. Carrier’s sizing guide and the DOE consumer guide both call for an ACCA Manual J load calculation rather than a square-footage rule. When we replace a furnace in a house that got new windows or attic insulation since the old one went in, we run the calculation again instead of matching the old nameplate.
Airflow problems
Carrier lists “poorly designed or sealed ducts” that restrict airflow and force the system to work harder, and dirty filters that make the blower motor strain. Bryant is blunter about the filter. “A clogged filter restricts airflow, causing the heat exchanger to overheat,” and one-inch filters generally need changing monthly. The DOE guide adds crushed or disconnected ductwork to the list. A furnace that keeps tripping its high-limit switch on a dirty filter is aging faster than its birthday says, and that is the pattern behind most of the calls in our furnace blowing cold air guide.
Corrosive basement air
This one is in the owner’s manual and almost nobody reads it. Carrier’s condensing furnace manual says combustion air “must be clean and uncontaminated with chlorine or fluorine,” compounds found in “water softener salts, laundry bleaches, detergents, adhesives, paints, varnishes, paint strippers, waxes, and plastics,” and that “if these compounds are burned in your furnace, the heat exchangers may deteriorate.” The 80 percent furnace manual puts it in capitals: do not “use your furnace room as a broom closet or a place to store any kind of chemical or cleaner.” In a lot of the basements we work in, the furnace shares a room with the washer, the water softener and a shelf of pool chemicals. A high-efficiency furnace adds one more item, since Carrier says improper condensate drainage “can lead to internal damage” and the manual wants the condensate system cleaned every year.
Climate cuts both ways in the sources, and we will report it as it reads rather than pick a side. Bryant says homes in the Northern US “require furnaces to run longer and harder than those in milder regions,” which adds operating hours and wear. The Department of Energy, in the same rule that produced the 22.5-year figure, assumed that “equipment operated for fewer hours will have a longer service lifetime” and found that furnaces in the North are generally higher capacity for the heating load and so “can have lower operating hours,” which is why its Northern average came out longer, not shorter. A Connecticut furnace works hard for five months and rests for seven. What that nets out to is the number in the table.
A Heil high-efficiency gas furnace from our job library. It vents in PVC and carries our service sticker on the door, and a condensing furnace like this one adds a condensate trap and drain to the yearly maintenance list.
Not sure how old your furnace is?
The data plate inside the door carries the brand, model and serial number, and we can date it on the phone. If it is under 15 and the repair is small, we will tell you to repair it.
Signs a furnace is near the end
None of these signs means the furnace is finished on its own. Each one means a technician should look, and the last row means leave the house first. The middle column is what the manufacturer or the Department of Energy says; the last is what we check when we get there.
| What you notice | What the source says | What we check |
|---|---|---|
| Heating bills climbing with no change in how you live | Bryant: “a decline in furnace efficiency” may be contributing. Carrier: “a sudden spike in energy bills.” | Combustion efficiency, the filter, duct leaks, the thermostat history. |
| A second or third repair in one winter | Bryant: “If you are calling a technician multiple times a winter, the cost of furnace repairs may soon outweigh the cost of a new, reliable system.” | The invoice history for the unit, and which parts have already been replaced. |
| Some rooms too hot, some too cold | DOE Energy Saver lists it as a reason to consider replacing. Bryant calls it “uneven heating.” | Airflow and the duct runs before we blame the furnace. |
| Banging, rattling or squealing | Bryant: noises “can indicate mechanical problems that warrant professional inspection.” | Blower bearings and wheel, the inducer, burner ignition. |
| A repair quote close to the price of a new unit | Carrier: “expensive repair bills that approach the cost of a new unit.” | The age, the part, and the math in our Southbury post below. |
| Soot, a yellow burner flame, a strong odor, or water pooling at the base | Bryant lists these as possible symptoms of a cracked heat exchanger, “a serious issue that often requires professional diagnosis.” | The heat exchanger itself, and carbon monoxide at the registers. See the box below first. |
If a carbon monoxide alarm sounds or you smell gas, leave first
The U.S. Consumer Product Safety Commission says: “If you suspect CO poisoning, get outside to fresh air immediately, and then call 911.” For a gas smell, Connecticut’s Public Utilities Regulatory Authority says not to use a telephone or flip light switches near it, and “if the odor is strong, leave the premises immediately and tell others to leave,” then call the gas company from a neighbor’s house or outside. “They will come and make the area safe at no charge to you.” Read the PURA gas safety page once now, before you need it. A cracked heat exchanger is a replacement, not a repair, and it is never a homeowner inspection.
Furnace replacement in Oxford, Southbury and Naugatuck: how age, repairs and efficiency add up
Age sets the clock. Carrier says the 15-year mark is when to start researching a replacement; Bryant says to start budgeting around 12 to 15 and, in the same breath, that “age alone does not determine when replacement is necessary.” We agree with Bryant. A 17-year-old furnace with a clean service file and a sound heat exchanger stays in the basement. A 12-year-old furnace that has eaten two blower motors and an inducer is a different conversation.
Repair history is the second factor, and it is the one you can see on paper. Bryant’s test is a technician visit “multiple times a winter”; Carrier’s is a repair bill that approaches the cost of a new unit. Our Southbury repair-versus-replacement post has the math we use, including the 50 percent rule, so we won’t repeat it here.
Efficiency is the third, and it is where the age of the furnace turns into a number on a bill. A new gas furnace sold today can still be an 80 percent AFUE unit like Carrier’s Comfort 80, or a 96 to 98.5 percent one like Bryant’s Evolution 96 and Carrier’s Infinity 98. ENERGY STAR’s bar for Connecticut is 97 percent. And the Department of Energy has adopted a 95.0 percent AFUE minimum for non-weatherized gas furnaces, signed September 28, 2023 and applying to furnaces manufactured five years after the rule’s publication in the Federal Register. The same rule acknowledges that the furnaces “that currently achieve 95-percent AFUE do employ condensing technology,” which is the PVC venting and condensate drain you see on a high-efficiency furnace today. What that costs in a Connecticut house, venting and ductwork included, is in our HVAC replacement cost guide.
If you are typing furnace replacement near me from Oxford, Southbury or Naugatuck, the shop that answers is at 1114 Middlebury Rd in Watertown, and all three towns have been inside our service area since 1978. We replace gas and oil furnaces, and the phone is answered around the clock at 203-756-5040.
Here is the one opinion in this post. Replace a furnace on your schedule, not on its. A furnace that fails in January gets replaced with what is in stock, on the coldest week of the year, with the house cold while the crew works. One that is replaced in October gets a load calculation, the right size, a venting plan and a quiet install. The age of your furnace tells you which of those two installs you are heading for.
Past 15? Find out what is actually worn
A heating system inspection reads the heat exchanger, the combustion numbers and the airflow, and tells you whether the furnace has winters left or a bill coming.
Frequently asked questions
How long does a gas furnace last in Connecticut?
Plan on 15 to 20 years. Carrier and Bryant both publish that range for a gas furnace that is maintained every year, and the U.S. Department of Energy’s lifetime analysis puts the average gas furnace in the North at 22.5 years. The furnaces we see reach the top of that range are the ones with a filter changed monthly and a fall service every year.
How long does an oil furnace last?
About the same. Carrier puts a well-maintained oil furnace at 15 to 20 years and says high-quality models can sometimes reach 30. The difference is upkeep: Carrier says oil furnaces typically need more frequent maintenance to prevent soot buildup, so the yearly burner cleaning matters more on oil than the equivalent visit does on gas.
Is it worth fixing a 20-year-old furnace?
Usually no, and the manufacturers say so. Carrier calls replacing a 20-year-old furnace “often the smart financial move,” and Bryant says it is generally not worth fixing one. The exception is a cheap part on a furnace with a sound heat exchanger and a clean history. Our Southbury repair-versus-replacement post has the rule we use.
Can a furnace last 30 years?
Some do. Carrier says a high-quality furnace can last up to 30 years with proper installation and consistent maintenance, and Bryant says the same “while rare.” The Department of Energy’s survey averages top out at 23.6 years, so 30 is the exception, and it is almost always a furnace that was sized right, kept clean and kept away from basement chemicals.
How do I find out how old my furnace is?
Open the upper door and read the data plate. It carries the brand, the model and the serial number. Lennox and Goodman each run a warranty lookup page that takes those details. Or read the plate to us on the phone and we will date it while you wait.
Do you handle furnace replacement near me in Oxford, Southbury and Naugatuck?
Yes. All three towns are inside the area we have served from Watertown since 1978, for gas and oil furnaces, and we answer 203-756-5040 around the clock for heating emergencies. Each town has its own page with the heating services we run there; the Oxford heating page is one, and the Southbury and Naugatuck pages are linked at the end of this post.
Thinking about one more winter on the old furnace?
Tell us the brand and the serial number from the data plate and we will date it on the phone. Family owned in Watertown since 1978. Licensed in Connecticut, HTG.0386984 and SHM.0005083.
Request a furnace replacement quoteRelated reading
About the author
American Heating and Air Conditioning Service
Family owned HVAC contractor, 1114 Middlebury Rd, Watertown CT 06795
We have installed and serviced gas and oil furnaces across the Greater Waterbury area since 1978, our technicians are NATE certified, and we answer the phone 24 hours a day for heating emergencies. Questions about anything in this article? Call us at 203-756-5040.
References and photo credits
- Carrier, How Long Does A Furnace Last? Average Furnace Lifespan Guide
- Bryant, How Long Does A Furnace Last? Furnace Lifespan Guide
- Carrier, Carrier Oil Furnace Guide
- Carrier, Infinity 98 Gas Furnace 59MN7 (warranty terms)
- Carrier, Comfort 80 Gas Furnace 58SB0 (warranty terms)
- Bryant, Evolution 96 Variable-Speed Gas Furnace 986T (warranty terms)
- Lennox, SLP99V Variable-Speed Gas Furnace (warranty terms)
- Carrier, Condensing Gas Furnace Owner’s Manual (OM9GFRC-02)
- Carrier, Non-Condensing 80% AFUE Gas Furnace Owner’s Manual (80GSFRN-C-03OM)
- Carrier, Calculating Furnace Size: What Size Furnace Do I Need?
- U.S. Department of Energy, Energy Conservation Program: Energy Conservation Standards for Consumer Furnaces, final rule (signed September 28, 2023)
- U.S. Department of Energy, Energy Saver Guide: Tips on Saving Money and Energy in Your Home (2022)
- U.S. Department of Energy, Consumer Guide to Home Heating and Cooling
- ENERGY STAR, Furnaces Key Product Criteria
- ENERGY STAR, Furnaces
- U.S. Consumer Product Safety Commission, Carbon Monoxide Information Center
- Connecticut Public Utilities Regulatory Authority, What To Do If You Smell Natural Gas
- Lennox, Warranty Lookup and Goodman, Warranty Lookup
References checked October 14, 2026. General homeowner information, not a substitute for the instructions supplied with your equipment or an on-site diagnosis. Every lifespan figure is the published range of the source named beside it; none is a guarantee for a particular furnace.
The hero is an editorial image generated from one of the company’s own job photos; it is not a photograph of a specific customer’s home. All other photos are American Heating and Air Conditioning Service job photos from the company’s own library.
Heating services from American Heating
The pages behind this post, for when the furnace is the next job on the list.
- Furnace replacement, repair and service across Greater Waterbury, gas and oil
- Heating services for the Greater Waterbury area, furnaces, boilers and more
- HVAC maintenance plans and service contracts, the yearly service that gets a furnace to 20
- Heating system inspection and testing for a furnace past 15
- Heating service in Oxford, furnace, boiler and hot water
- Heating service in Southbury, furnace, boiler and hot water
- Heating service in Naugatuck, installation, maintenance and repair
- Contact us for 24/7 emergency service, or call 203-756-5040
Heating tips in your inbox
One short email when we publish a new guide for Greater Waterbury homeowners. No sales blasts. Unsubscribe anytime.
