Old boiler replacement cost when buying a house

How much does it cost to replace an old boiler?

Replacing an old boiler usually costs $4,290 to $10,070 installed, and fuel type, size and efficiency set where you land (table below). Before your inspection deadline, have a licensed heating contractor look at the boiler and give you a written bid. Age alone won't tell you whether it needs replacing. The bid will, and it's the number your request should carry.

Key takeaways

• If the replacement is another naturally drafted boiler, the bid should include a combustion safety test.
• Natural-draft boilers usually run at 70% AFUE or less, while ENERGY STAR gas boilers are rated 90% or higher.
• A standard homeowners policy typically won't pay to replace a boiler that broke down, so price it before you close.

What does a new boiler cost?

What a new boiler will cost you depends mostly on scope, so match each row to what your contractor will quote.

Kept prices every line of an inspection report for $79, usually under 4 hours, and marks the ones that need a professional quote.

This Old House says to expect more if the system needs piping repairs or electrical upgrades. A 2,000-square-foot house usually needs a boiler rated 60,000 to 100,000 British thermal units per hour, and This Old House prices that at $5,000 to $8,000, with brand and local labor moving the price. Get a written bid.

For how the other heating lines on your report price out, see heating and cooling findings on an inspection report. If your report says furnace rather than boiler, read old furnace on an inspection report instead.

Is an old boiler dangerous?

The safety question on an old boiler is venting. On a gas boiler, combustion gases can spill back into the house instead of going up the flue. Many older gas boilers use an open draft hood and are called natural draft. InterNACHI (the International Association of Certified Home Inspectors) says they "rely entirely on a high flue temperature relative to the outside temperature to draw exhaust gases up and out of the flue." Newer ones add a small fan that "helps to prevent backdrafting on startup," but InterNACHI says either type can backdraft.

That matters because of carbon monoxide (CO), and oil-fired boilers are combustion devices too. The Environmental Protection Agency (EPA) lists "worn or poorly adjusted and maintained combustion devices (e.g., boilers, furnaces)" as a CO source. It warns that "CO can kill you before you are aware it is in your home," and says to have a trained professional inspect, clean and tune up your central heating system annually. That applies whether the boiler burns gas or oil.

If the report mentions backdrafting, a rusted flue or a CO reading, get a licensed heating contractor out before your deadline. If you suspect CO poisoning, the Consumer Product Safety Commission (CPSC) says to "get outside to fresh air immediately, and then call 911." If you smell gas, leave the house first, then call the gas utility or 911 from outside. In either case, don't run the boiler again until a licensed heating contractor has checked it. For that finding on its own, see backdrafting or a rusted flue on an inspection report.

How old is too old for a boiler?

No single age makes a boiler too old, because lifespan figures disagree. InterNACHI's life-expectancy chart lists a hot-water and steam boiler at 40 years, assuming regular maintenance and normal wear. Carrier, which makes boilers, says they typically last 15 to 25 years with proper maintenance.

A 12-year-old boiler is under both figures. A 20-year-old one sits inside both, and a 50-year-old one is past both. Ask the seller for the boiler's service records, since InterNACHI's figure assumes regular maintenance. Either way, the contractor's look at condition, venting and efficiency decides repair or replace.

Efficiency is part of that call. InterNACHI says natural-draft boilers usually have an annual fuel utilization efficiency (AFUE) of 70% or less. If you replace an old gas boiler, ENERGY STAR certified gas boilers are rated 90% AFUE or higher and use sealed combustion that draws outside air for the burner.

Who can check the boiler before my deadline?

A licensed heating contractor can check the boiler before your deadline. Ask for three things in writing: whether the boiler is natural draft or has a draft fan, whether it should be repaired or replaced, and the price for that scope. InterNACHI says that when a natural-draft unit goes in, "a combustion safety test must be performed." Check that line is in the bid.

Also ask whether the pipes or the boiler jacket are wrapped in insulation that needs testing before removal. The EPA lists hot water and steam pipes coated with asbestos material, and oil and coal furnaces with asbestos insulation, among the places asbestos turns up in older homes. Testing and removal may not be in the replacement bid, so ask for it to be priced.

For how to get a contractor out fast, see how to get repair estimates during the inspection period.

What should I ask the seller for?

Ask for one of two things: replacement by a licensed contractor, or a credit equal to your written bid. Put the bid's scope and total in the request, not a cost-guide range. If the contractor says repair, ask for the repair instead.

What to ask for after a home inspection covers how this line fits your list, and the buyer repair request letter template gives you the wording.

What if the seller says no?

If the seller says no, you can accept the house and budget the bid yourself, ask for a smaller credit, or cancel inside your inspection contingency. Your contract sets the exact dates and terms, so confirm them with your agent. A priced boiler is a known cost, which is different from a finding nobody can price. When to walk away after a home inspection walks through that choice.

Will homeowners insurance pay to replace an old boiler?

Homeowners insurance usually won't pay to replace a boiler that wore out. Progressive says "a standard homeowners policy typically won't cover the cost to repair or replace boilers if there was a mechanical problem." It adds that you may be able to buy an equipment breakdown endorsement. Ask your insurance agent what your policy covers before you close.

How do I know what the rest of my report is worth?

The rest of your report is worth what each line costs to fix, and the boiler is only one line. Upload your inspection report to Kept so your days go to the contractor's visit, not the rest of the list.

Sources

• Carrier, Boiler Installation Cost and Replacement Guide
• This Old House, How Much Does Boiler Replacement Cost?
• InterNACHI, Inspecting Gas-Fired Boilers
• InterNACHI, Standard Estimated Life Expectancy Chart for Homes
• EPA, Carbon Monoxide's Impact on Indoor Air Quality
• CPSC, Carbon Monoxide Information Center
• ENERGY STAR, Boilers
• EPA, Learn about Asbestos
• Progressive, Does homeowners insurance cover a furnace or boiler?