The furnace is not working, so have a heating company call you.

Smell is the first split. Natural gas is odorless until the utility adds an odorant. Carbon monoxide has no smell at all. If either one is in the house, the first minute is leaving. The thermostat can wait until the air is safe.

Leave if you smell gas or a CO alarm is sounding

If you smell gas, leave the house now. From outside, call your gas utility's emergency number. ComfortSystems says to leave the building, and not to use a phone, flip an electrical switch, light a match, or start a car. It says not to do anything that could create a spark or ignite a flame.

Minnesota Energy Resources says natural gas is odorless until mercaptan is added, an odorant similar to rotten eggs. If you smell gas, or you have a gas emergency, that page says to leave immediately and call them from another location. Their leak number is 800-889-4970. That number is for their customers. The same company's emergency page lists 800-889-4970 for a gas odor, and says that for carbon monoxide, leave the building and call 911.

If you are not a Minnesota Energy Resources customer, use your own gas utility's leak number. MidAmerican tells its customers to leave the area immediately and call the utility and 911 from a safe distance.

The CPSC says that if a carbon monoxide alarm sounds, do not look for the source. Move outside to fresh air, call 911, count the people who were in the house, and do not go back in until emergency responders say you can. The EPA describes carbon monoxide as an odorless, colorless, toxic gas, and lists leaking chimneys and furnaces, and a blocked or disconnected flue, among the sources.

If anyone has symptoms the CPSC lists for low to moderate poisoning (headache, fatigue, shortness of breath, nausea, or dizziness), the CPSC says to get outside to fresh air right away and call the fire department from a neighbor's home. Tell a doctor you suspect carbon monoxide. The CPSC also says to install a carbon monoxide alarm that meets UL 2034 on every level of the home and outside sleeping areas. The CPSC says an alarm is no substitute for proper use and upkeep of appliances that can make carbon monoxide.

If the heat is out and you do not smell gas

If there is no heat in the house and no gas smell, the National Weather Service cold-weather sheet has a line for it: if your heat goes out, you can keep warm indoors by closing off rooms you do not need, dressing in layers of lightweight clothing, and wearing a cap.

That sheet also says never to use a gas oven to heat your home, and never to run a generator indoors. The CPSC says the same two things. Minnesota Energy Resources says never to use an oven or range to heat a home, and to have a qualified contractor inspect furnaces, vents, and chimneys at least every other year. The CPSC's inspection line is annual: have the heating system professionally inspected and serviced every year, including chimneys and flues.

ENERGY STAR says to inspect, clean, or change the furnace air filter once a month.

Keep the pipes from freezing

On the same weather service sheet, the pipe steps are: let hot and cold water trickle or drip at night from a faucet, open cabinet doors so more heat reaches uninsulated pipes under a sink or near an outer wall, and make sure you know how to shut the water off in case a pipe bursts.

The sheet also says to leave the heat on and set it no lower than 55 degrees. That line assumes the furnace can still heat the house. If the furnace is already out, use the drip, the open cabinets, and the shutoff from What keeps pipes from freezing?.

If a pipe is frozen, the sheet says never to thaw it with an open flame or a torch. Use a hair dryer. Be careful of electric shock in and around standing water.

What a national repair page lists

HomeAdvisor, updated June 20, 2026, says furnace repair costs average $318, with a normal range of $133 to $505. The same page gives a wider range of $64 to $1,475. Those figures are national, not a bid for your house.

Repair, replace, rebates

ENERGY STAR says to consider replacing a furnace or boiler that is more than 15 years old, and that an ENERGY STAR furnace is 15% more efficient than a conventional furnace. It also lists frequent repairs and rising energy bills as reasons to look at a replacement. What does a furnace repair cost? has the national Angi range.

AFUE, annual fuel utilization efficiency, is the rating utilities use for furnace rebates. A rebate and an instant discount are different. MidAmerican takes a rate off the purchase price through a participating provider, for its own customers. ComfortSystems in Duluth pays a stated dollar amount after a qualifying furnace is in. What furnace rebates are there in 2026? has the amounts for Duluth, Rochester, and Iowa.

The federal piece changed. The IRS calls it the section 25C energy efficient home improvement credit. An IRS FAQ on the July 4, 2025 law says the credit is not allowed for property placed in service after December 31, 2025. The dated post quotes both IRS pages. A furnace installed in 2026 is after that date.

Permits, if the job becomes a replacement

A repair visit and a replacement permit are different. Duluth, Rochester, Sioux Falls, and Cedar Rapids each write the permit rule on the city page: Duluth, Rochester, Sioux Falls, and Cedar Rapids.

Do you want to talk through the furnace?

You can follow the pipe steps yourself. If the furnace will not light, the vents blow cold, or you do not want to open the unit, a heating company can look at it. How to choose a furnace repair company is a checklist for any company, including the companies that may call you through this site. Asking for that call does not hire them.

Questions people ask next

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