How much does a new boiler cost in Minnesota?
National cost guides such as HomeGuide put a typical gas boiler replacement at $4,000–$9,000 and a high-efficiency boiler at $4,000–$10,000, with standard-efficiency boilers starting around $2,200. We quote boilers in writing after seeing the system, because steam or hot water, the radiators, the venting and the chimney move the price most.
Key points
- HomeGuide's typical national ranges: $4,000–$9,000 for a gas boiler replacement and $4,000–$10,000 for a high-efficiency boiler.
- We quote boilers in writing after seeing the system; steam or hot water, the radiation and the venting move the price most.
- Condensing and combi boilers are for hot-water systems; a steam house gets a steam boiler sized to its connected radiation.
- The radiators usually stay; the chimney and the water heater's venting are the common surprises.
- About two in five housing units in Minneapolis and Saint Paul were built in 1939 or earlier, and many still heat with radiators.
National cost guides such as HomeGuide put a typical gas boiler replacement at $4,000–$9,000 and a high-efficiency boiler at $4,000–$10,000, with standard-efficiency boilers starting around $2,200. Those are national figures, not Minnesota prices or our quote: we price a boiler in writing after we've seen whether the house runs on steam or hot water, how much radiation it has, and where the new boiler will vent.
The boiler is what people shop for, but the chimney, the water heater's venting, the piping at the boiler and the system it feeds often decide the final number.
The national ranges
| Item | Typical national range (HomeGuide, 2026) |
|---|---|
| Gas boiler replacement | $4,000–$9,000 |
| High-efficiency boiler | $4,000–$10,000 |
| Standard-efficiency boiler | starting around $2,200 |
| Oil-to-gas furnace or boiler conversion | $6,000–$20,000 |
| Chimney liner (listed in that conversion guide) | $1,500–$4,000+ |
HomeGuide bases these on research and project costs its members report nationally, and it names size, efficiency, venting and piping changes among the drivers. We don't publish our own boiler range, because a steam boiler in a 1910s house with its original radiators and a wall-hung boiler on a newer radiant-floor system are different jobs. If you're leaving oil behind, our oil-to-gas conversion guide covers that side.
Cast iron, condensing or combi
| Boiler type | Fits | Venting | What it adds to the job |
|---|---|---|---|
| Cast-iron hot-water, non-condensing | Large radiator systems, houses keeping the chimney | Usually the chimney, checked for a sound liner and good draft | The fewest extras, but lower efficiency than condensing |
| Cast-iron steam | Every steam system | Usually the chimney | Sizing by measuring radiators; piping at the boiler built to the new boiler's instructions |
| Wall-hung condensing (modulating) | Hot-water systems: radiators, baseboard, radiant floors | Usually plastic vent pipe out a side wall, plus a condensate drain | An outdoor reset control, and often a venting fix for the water heater |
| Combi (condensing) | Smaller homes with modest hot-water use | Same as condensing | Replaces the water heater too |
U.S. Boiler Company puts non-condensing boilers typically at 80%–88% efficiency and condensing boilers usually above 88%, and ENERGY STAR-certified gas boilers are rated at 90% AFUE or better. A condensing boiler only reaches its rating when the water coming back to it runs cool, so it pays off most on radiant floors and on radiators that can heat the house with cooler water on mild days. An outdoor reset control helps by lowering the water temperature as the heating load drops. Our radiant floor vs baseboard guide explains the water-temperature side.
A combi boiler, like the Navien combi boilers we service, heats the house and makes hot water on demand. A busier household with several bathrooms in use at once usually does better with a boiler and an indirect water heater, which uses the boiler's hot water to heat a storage tank.
Why do steam boiler quotes differ from hot-water quotes?
- Steam stays steam. Weil-McLain describes a condensing boiler as a hot-water heating system, so a steam house gets a new non-condensing steam boiler. Converting the whole system to hot water is a far bigger job than a boiler swap.
- Steam is sized to the radiators. A hot-water boiler is sized to the house's heat loss, which we work out with a Manual J load calculation. A steam boiler is sized to the radiation connected to it. U.S. Boiler Company explains that you add up the square feet of radiation on the system, count an uninsulated steam main like another radiator, and expect the boiler to make roughly a third more steam than the radiators need to cover piping losses and pickup. More steam than the system can use can make the boiler short-cycle. So a steam quote starts with someone measuring every radiator.
- The piping at the boiler matters. It has to follow the new boiler's installation instructions, and the low-water cutoff and pressure control get set and tested at startup.
Do the radiators stay when you replace a boiler?
The radiators almost always stay. Cast-iron radiators and their piping usually outlast the boilers that feed them, so the work happens at the boiler: the boiler, its controls, the piping beside it, and on hot-water systems often the circulator and expansion tank.
Radiators were sized for the house as it was built. If the walls, attic or windows have been improved since, the same radiators can keep the house warm with cooler water for much of the season, which is when a condensing boiler condenses. Before a new boiler goes in, the system gets checked for leaks, stuck valves and trapped air, since a new boiler won't fix a problem out at a radiator. Our post on boiler banging and kettling covers the usual culprits.
Does a new boiler change the chimney and venting?
A cast-iron boiler usually vents into the chimney the same way the old one did, and the chimney's liner and draft get checked as part of the quote. A condensing boiler leaves the chimney and vents through plastic pipe out a side wall. In Minnesota, where that pipe exits matters: a termination that drifts over with snow shuts the boiler down on the night you need it most. Sealed-combustion boilers draw their combustion air from outdoors, which ENERGY STAR notes reduces drafts and improves safety.
The catch is the water heater. Once the boiler leaves the chimney, a gas water heater left behind vents alone into a flue sized for two appliances, and it may need a liner or a different vent. HomeGuide's conversion guide lists a chimney liner at $1,500–$4,000+ nationally, and that fix belongs on the written quote from the start. A combi boiler removes the question when it replaces the water heater.
Why do Minneapolis and Saint Paul have so many boilers?
Age, mostly. About 41% of Minneapolis housing units and 42% of Saint Paul's were built in 1939 or earlier, according to the U.S. Census Bureau's 2024 American Community Survey estimates. Houses of that era were commonly heated with steam or hot-water radiators, or with gravity warm-air furnaces that were later converted to forced air. Where the radiators stayed, they're still working, because radiators outlast boilers and owners would rather replace a boiler than cut ducts into plaster walls. That's why so much boiler work in both cities is one boiler replacing another in a foursquare, bungalow, Victorian or duplex that still has its original radiators.
If you're weighing a switch to a furnace, boiler vs furnace for Saint Paul homes covers when that makes sense. Our pages on boiler service in Saint Paul and boiler service in Minneapolis cover each city, and the Saint Paul cost page puts boilers next to every other system.
When should you replace a boiler instead of repairing it?
ENERGY STAR suggests considering replacement once a boiler is more than 15 years old, and says an ENERGY STAR boiler is about 5% more efficient than a new standard model. Age alone doesn't settle it, though: Lennox puts boiler life at 15–30 years, and a well-kept cast-iron boiler can sit at the long end of that. The usual reasons to replace are a leaking heat exchanger or cast-iron section, burner or control parts that are no longer made, and repair bills stacking up on an old boiler.
A repair visit is the inexpensive way to find out. It's a $79 trip charge, waived when you approve the repair, with a written flat-rate price before any work. Maintenance visits run $129–$349 depending on the equipment.
Rebates and permits
- CenterPoint Energy (gas in Minneapolis) runs heating system rebates that cover high-efficiency boilers, with the dealer of your choice. The equipment has to be installed in 2026, and the application has to go in the same calendar year.
- Xcel Energy (gas and electricity in Saint Paul) lists gas boiler rebates. Some Xcel measures need a registered contractor, so ask before you buy.
- Steam boilers: a non-condensing steam boiler may not meet a rebate's efficiency floor, so confirm before counting on one.
- Federal: the 25C tax credit ended for equipment placed in service after December 31, 2025.
- Permit: a boiler replacement normally needs a mechanical permit, and our permit guide explains the process in both cities.
Safety stops
- Never cap or plug a boiler's pressure relief valve. A dripping valve means the pressure or the expansion tank needs attention.
- Minnesota law (Minn. Stat. 299F.51) requires an approved, operational carbon monoxide alarm within ten feet of each room lawfully used for sleeping. The Minnesota Department of Health says never to ignore a sounding CO alarm, and if anyone has symptoms, to leave the building and call the fire department.
- If you smell gas, leave the house and call your gas utility or 911 from outside.
What to do next
Call 612-429-3465 (open 7 days, 7am–9pm) to set up a visit. We'll confirm steam or hot water, measure the radiation or run the heat-loss calculation, look at the chimney and the water heater, and write up the options with model numbers, venting and the permit spelled out. Installs carry our 2-year labor warranty on top of the manufacturer's parts warranty, and financing is available. Our boiler service page covers repairs and tune-ups in the meantime.
Questions
Can I replace my steam boiler with a condensing boiler?
Not on a steam system. Condensing boilers are hot-water boilers, so a steam house gets a new non-condensing steam boiler sized to the radiation connected to it. Converting the whole house to hot water means reworking the piping and often the radiators, a much bigger job than a boiler swap, so most steam homes replace steam with steam.
Do I have to replace my radiators when I replace the boiler?
No. Cast-iron radiators and their piping usually outlast several boilers, and the new boiler connects to them. The work happens at the boiler: the boiler itself, its controls, the piping beside it, and on hot-water systems often the circulator and expansion tank. Leaks, stuck valves or trapped air out at the radiators should be fixed before the new boiler goes in.
Why do boiler replacement quotes vary so much?
Because they often don't include the same work. One quote may reuse the chimney without checking the water heater's venting, size a steam boiler from the old nameplate instead of counting radiators, or leave off the permit. Another includes a chimney liner, an indirect water heater or a system cleanout. Compare model numbers, the sizing method, the venting plan and what happens to the water heater.
Are there rebates for a new boiler in Minnesota?
Utility rebates, yes. CenterPoint Energy's heating system rebates cover high-efficiency boilers with the dealer of your choice, and Xcel Energy lists gas boiler rebates, some tied to a registered contractor. A non-condensing steam boiler may not meet a rebate's efficiency floor, so check first. The federal 25C tax credit ended for equipment placed in service after December 31, 2025.
Sources
- HomeGuide cost guides (2026 editions) homeguide.com
- ENERGY STAR energystar.gov
- Minnesota Department of Health health.state.mn.us
- U.S. Environmental Protection Agency epa.gov