Ask what a furnace repair costs and the honest answer is that it depends on what is wrong, and on what the quote includes. Two companies can look at the same furnace and hand over numbers that are far apart. That is not always a sign that one of them is wrong. It can be a sign that they are quoting different things.
This guide does not give prices. It explains what goes into a repair quote, why two quotes can differ, and how to compare them so that the choice is between like and like. It draws on the Federal Trade Commission’s advice on estimates and contracts, ENERGY STAR’s advice on hiring a heating contractor, and the terms in one furnace manufacturer’s installation manual.
What a repair quote is made of
A repair quote has a small number of parts, whatever the total:
- The diagnosis. What the technician found, and how they found it.
- The work. What will be done to fix it.
- The parts. What will be replaced, by model or part description.
- The labour. The time the work will take.
- The terms. When the work will happen, and what warranty covers it.
The Federal Trade Commission’s list of what a written estimate should contain matches that closely: “A written estimate should include a description of the work to be done, materials, completion date, and the price.” ENERGY STAR’s advice is to “get written, itemized estimates,” and when comparing them, “be sure to compare cost, energy efficiency and warranties.”
An itemised quote is the one that can be compared. A single number with no breakdown cannot.
Why two quotes for the same furnace differ
When two quotes are far apart, look for the reason in the parts above. Working out which is the whole job of comparing them.
A different diagnosis
The first question is whether both companies found the same fault. A repair quote is only as good as the diagnosis behind it, and a diagnosis is a matter of measurement. The furnace manual gives the numbers a technician should be able to check: a furnace must be installed “with a duct system which has external static pressure within the allowable range, as specified on the furnace rating plate,” and “the air temperature rise must be within the range listed on the furnace nameplate.”
ENERGY STAR’s maintenance checklist shows how much a heating visit can cover. Its heating-specific item reads: “Check all gas (or oil) connections, gas pressure, burner combustion and heat exchanger.” It explains why: “A dirty burner or cracked heat exchanger causes improper burner operation. Either can cause the equipment to operate less safely and efficiently.” Its general items include “check controls of the system to ensure proper and safe operation” and “check the starting cycle of the equipment to assure the system starts, operates, and shuts off properly.” A diagnosis that covers those points and one that stops at the first fault found can reach different conclusions about the same furnace.
Ask each company what it measured and what it found. If one quote replaces a part and the other replaces a different part, the diagnosis is the disagreement, and the price difference follows from it.
A different scope
One quote may fix the fault you called about. Another may include other work the technician recommends. Neither is wrong in itself, but they are not the same job. Ask each company to separate what is needed to restore heat from what is recommended, and to say why.
Sometimes the scope difference is bigger: one company quotes a repair and another recommends replacement. That is a different decision, with its own questions about the furnace’s age and condition. ENERGY STAR’s advice for a replacement quote is to “expect a home evaluation”: “The contractor should spend significant time inspecting your current system and home to assess your needs. A bigger system isn’t always better; a contractor should size the heating and cooling system based on the size of your house, level of insulation, and windows.” A replacement quote built without that evaluation is not comparable with one built on it. ENERGY STAR’s point about comparing “cost, energy efficiency and warranties” applies with more force there, because a replacement changes all three.
A different warranty position
Warranty can change what a repair costs you, and it depends on the furnace and its paperwork.
One manufacturer’s installation manual illustrates both sides. On registration, it says: “Though not required to get the protection of the standard warranty, registering your product is a relatively short process, and entitles you to additional warranty protection.” On exclusions, it lists installation requirements and states: “Damage or repairs due to failure to comply with these requirements are not covered under the warranty.” It also says: “Damage or repairs due to the installation of the furnace without filters is not covered under the warranty.”
Every manufacturer’s terms are their own. The point is that whether a part is under warranty, and whether the furnace was registered, can change a quote, and a company that checks may quote differently from one that does not. Have your furnace’s model and serial number ready, and ask each company whether it checked warranty status.
A different timing
A visit at night or at a weekend may be charged differently from one in business hours. That is a question to ask before the visit, not a figure this guide can give. If the furnace can safely wait until morning, the timing is part of the choice. When it cannot wait, see emergency HVAC repair.
Permits
Some heating work needs a building permit, and the town decides which. The FTC lists a warning sign worth knowing here: “Scammers ask you to get any required building permits.” A legitimate contractor knows when a permit is needed and handles it. If one quote includes a permit and another does not, ask why.
How to compare two quotes
The FTC’s advice is short and worth following as written: “Get multiple estimates.” “Don’t automatically choose the lowest bidder. And ask for an explanation if there’s a big difference among the estimates.”
ENERGY STAR makes the same point about price: “A lowest price may not be the best deal if it’s not the most efficient because your energy costs will be higher.” For a repair, efficiency matters less than it does for a replacement, but the principle holds. The cheaper quote is only cheaper if it fixes the same fault with the same parts and the same warranty.
A practical way to compare:
- Put the two diagnoses side by side. Are they the same fault?
- Put the parts side by side. Are they the same parts, or equivalent ones?
- Put the warranties side by side, for both the parts and the labour.
- Ask each company to explain anything the other included and it did not.
If one company will not explain its quote, that is information too.
Checking who is quoting
The FTC’s first piece of advice for avoiding a bad contractor is about the company, not the price: “Consider only contractors who are licensed and insured. Check with your state or county government to confirm a contractor’s license, and ask the contractor for proof of insurance.”
It also suggests checking the company’s record: “Check with the local Home Builders Association and consumer protection officials to see if they have complaints against a contractor.” And for reviews: “Read reviews with a critical eye.”
ENERGY STAR adds references: “Ask contractors for customer references and call them. Ask about the contractor’s installation or service performance, and if the job was completed on time and within budget.”
Before you sign anything
ENERGY STAR’s advice is to “get it in ink”: “Sign a written proposal with a contractor before work gets started. It’ll protect you by specifying project costs, model numbers, job schedule and warranty information.”
The FTC’s list of what a contract should include before you sign covers “the contractor’s name, address, phone number, and license number,” “an estimated start and completion date,” and “any promises made during conversations or calls related to issues such as the scope of work and the cost of labor and materials.” It adds: “make sure all blank spaces are filled in.”
On payment, the FTC is direct: “Don’t pay the full amount for the project up front.” And: “never make the final payment until the work is done and you’re satisfied with it.”
Warning signs
The FTC lists tactics that point to a contractor who may not be reputable. Among them:
- “Scammers knock on your door looking for business because they are ‘in the area.'”
- “Scammers pressure you for an immediate decision.”
- “Scammers ask you to pay for everything up front or only accept cash.”
- “Scammers suggest you borrow money from a lender they know.”
Pressure to decide on the spot is the one to watch for with a furnace in winter, when the house is cold and the temptation is to agree to anything. The FTC’s advice holds: “Don’t let anyone pressure you into signing any document.”
Before you call: what to have ready
ENERGY STAR’s first tip is to “study up”: “before you call a contractor, know the model of your current system and its maintenance history. Also make note of any uncomfortable rooms.” For a repair, that means the model and serial number from the furnace’s rating plate, when it was last serviced, and what it is doing: when it stopped, what the thermostat shows, and anything you heard or smelled.
A few safe checks can also save a call altogether:
- The thermostat. Set to heat, set above the room temperature, and working.
- The filter. The furnace manual says that “improper filter maintenance is the most common cause of inadequate heating or cooling performance.”
- Clearances. Registers open, return grilles clear, and nothing stored against the furnace.
- The carbon monoxide alarm. Test it. If it sounds, leave the house and call from outside.
For what the symptoms can mean, see furnace won’t turn on, furnace blowing cold air and how a furnace’s safety switches work. For repairs, see furnace repair.
If something goes wrong
The FTC’s advice if a job goes badly is to “first try to resolve it with the contractor,” to keep “notes and copies of letters and documents,” and, if that fails, to consider “your state attorney general or local consumer protection office.” The written estimate and the signed proposal are what make that possible.
Frequently asked questions
How much does furnace repair cost? It depends on the diagnosis, the parts, the labour, the timing and the warranty position, which is why this guide does not give a figure. Ask for a written, itemised estimate, which the FTC says should include “a description of the work to be done, materials, completion date, and the price,” and compare quotes item by item.
How much is a service call on a furnace? Ask before the visit what the service call charge includes, whether it covers the diagnosis, whether it is credited against the repair, and whether the time of the visit changes it. Those answers matter more than a number from someone else’s price list.
What is the most expensive repair on a furnace? This guide does not rank repairs by cost. What decides the cost of any repair is the part, the labour and whether the part is under warranty, and one manufacturer’s manual says registering the product “entitles you to additional warranty protection.” Check warranty status before paying for a major part.
What are the most common furnace repairs? No primary source reviewed for this guide ranks repairs. One furnace manual does name a cause: “Improper filter maintenance is the most common cause of inadequate heating or cooling performance.” Checking the filter before calling costs nothing.
Why do HVAC quotes differ so much? Because they can be quoting different things: a different diagnosis, a different scope of work, different parts or a different warranty position. The FTC’s advice is not to “automatically choose the lowest bidder” and to “ask for an explanation if there’s a big difference among the estimates.”
What is the $5,000 rule for a furnace? It is a rule of thumb for deciding between repair and replacement, with no standards body behind it. It is not a substitute for a diagnosis, and it does not account for warranty coverage or the furnace’s condition.
Sources
- Federal Trade Commission, How To Avoid a Home Improvement Scam (July 2022) – https://consumer.ftc.gov/articles/how-avoid-home-improvement-scam
- ENERGY STAR, 10 Tips for Hiring a Heating and Cooling Contractor – https://www.energystar.gov/saveathome/heating-cooling/10-tips-hiring
- ENERGY STAR, Maintenance Checklist – https://www.energystar.gov/saveathome/heating-cooling/maintenance-checklist
- Goodman, Installation Instructions for *M9S80 & *C9S80 gas furnaces (static pressure, temperature rise, warranty exclusions, product registration, filter maintenance) – https://documents.alpinehomeair.com/product/goodmangm9s8gc9s8installationmanual.pdf
