Cracked heat exchanger cost: replace or new furnace?

How much does it cost to replace a cracked heat exchanger?

A cracked heat exchanger can leak carbon monoxide, so get a licensed heating, ventilation and air conditioning (HVAC) technician to confirm it and price it in writing before your deadline. Furnace maker Trane puts the cost of replacing a cracked heat exchanger at $1,000 to $3,000, and a Denver-area contractor quotes as much as $5,000. On an older furnace, a whole new furnace may be the better ask.

Key takeaways

• Inspectors who follow the International Association of Certified Home Inspectors (InterNACHI) standards aren't required to evaluate heat exchangers, so the technician's diagnosis is the one to negotiate from.
• The heat exchanger's parts warranty doesn't cover labor, and labor is most of the bill.
• At one Upper Ohio Valley contractor's prices, a basic new furnace costs $200 to $600 more than its top price for an out-of-warranty heat exchanger.

Is a cracked heat exchanger dangerous?

Yes, it's dangerous. The heat exchanger keeps combustion gases out of the air you breathe. Lennox calls a crack "a serious safety risk" that can let out carbon monoxide, "a colorless, odorless, and potentially deadly gas." Trane says a cracked heat exchanger "can leak combustion gases into your home."

Your inspector may have seen the crack, or only its warning signs, such as soot or yellow flames. InterNACHI's Standards of Practice say an inspector is "not required to: inspect, measure, or evaluate the interior of flues or chimneys, fire chambers, heat exchangers." The line on your report is a reason to call a technician, not the final word.

If you suspect carbon monoxide poisoning, the Consumer Product Safety Commission says to "get outside to fresh air immediately, and then call 911." Treat a sounding carbon monoxide alarm the same way, then call a licensed HVAC professional. For a suspected crack with no alarm, Lennox's first step is "Shut off the furnace," and it warns that running a furnace with a damaged heat exchanger "can result in carbon monoxide leaks." The furnace isn't yours yet, so send the finding to your agent in writing today.

What does a heat exchanger replacement cost?

Heat exchanger prices differ mostly by scope and warranty. Labor drives the replacement cost, because the technician takes the furnace apart to reach the part. High-efficiency furnaces, rated 90 or higher on the annual fuel utilization efficiency (AFUE) scale, have a primary and a secondary heat exchanger, per Trane. Furnaces below 90 have one. Ask your technician which one is cracked, since the secondary has its own, lower price line in the table below.

Is it better to replace a heat exchanger or get a new furnace?

The age and warranty of the furnace decide it. Trane says a heat exchanger should last 10 to 15 years or more with good maintenance. If a 15-year-old furnace keeps needing costly repairs, Trane suggests considering a new furnace.

Warranty cuts the other way. Plumb-Line, a Denver contractor, says most makers warranty the heat exchanger part for 10 years to a limited lifetime. That covers only the part, not the labor. Installer labor warranties run 1 to 5 years. Plumb-Line's rule: under labor warranty, replace just the heat exchanger; over 10 years old with no labor warranty, replace the furnace.

Here's how that plays out on an older furnace with no warranty left, at one local contractor's prices. Honest Fix, in the Upper Ohio Valley, quotes up to $4,000 for the heat exchanger out of warranty and $4,200 to $4,600 installed for its basic 80% efficiency furnace. So the new furnace costs $200 to $600 more than the top repair price ($4,200 minus $4,000, and $4,600 minus $4,000). Four Seasons, a Portland-area contractor, adds that new furnaces come with new warranties.

Who confirms it before your deadline?

A licensed HVAC technician confirms it. Lennox says a technician can confirm a crack with combustion analysis or a visual inspection. Ask for a written diagnosis that covers four things:

• Whether the crack is confirmed, and in which heat exchanger
• The furnace's age and warranty status
• A price for the heat exchanger alone
• A price for a new furnace

The contractor who installed the furnace can tell you whether it is still under warranty, per Plumb-Line. For how fast you can get a bid, see how to get repair estimates during the inspection period.

What should you ask the seller for?

Ask for the fix your technician recommends, whether that's a new heat exchanger or a new furnace, at the technician's written price. Name the scope, the trade and the bid in the request. If the seller has the work done, ask for the technician's invoice showing what was replaced.

Kept prices every line of an inspection report for $79, usually under 4 hours, and marks the ones that need a professional quote. What to ask for after a home inspection covers how this line fits your list, and the buyer repair request letter template gives the wording around it.

What if the seller says no?

If the seller says no, most inspection contingencies let you cancel inside the window. Your contract sets the exact dates and terms, so confirm them with your agent or attorney. Before you decide, set the seller's answer against the technician's written price. When to walk away after a home inspection covers how to weigh it.

Can a cracked heat exchanger be repaired instead of replaced?

Trane says, "We wouldn't recommend trying to repair a cracked heat exchanger." Lennox says "repairs are rarely recommended." If a bid proposes a patch, ask the technician to explain why in writing.

How long does a heat exchanger replacement take?

A heat exchanger replacement takes up to 8 hours or longer, per Plumb-Line. Honest Fix says labor takes 6 to 10 hours.

What if my report has other heating findings?

Put a price on every line before you send the request.

If the heat exchanger is one line of many and your deadline is close, upload your inspection report to Kept so your time goes to the lines that need a technician's bid.

Sources

• Trane, "Cracked Heat Exchanger: What Does It Mean?"
• Lennox, "What to Do If Your Furnace Has a Cracked Heat Exchanger"
• InterNACHI, Home Inspection Standards of Practice
• Consumer Product Safety Commission, Carbon Monoxide Information Center
• HomeAdvisor, "How Much Does Heat Exchanger Replacement Cost"
• Four Seasons Heating and Air Conditioning, "Replacing a Heat Exchanger: Is It Worth It?"
• Plumb-Line Services, "Should I Replace My Heat Exchanger or Buy a New Furnace?"
• Honest Fix, "Cracked Heat Exchanger: Dangers, Symptoms & Costs"