The average heat exchanger replacement cost is $2,400 for the part and labor, though a range of about $1,000 to $4,500 is possible when the part is not under warranty.
If the heat exchanger is under warranty, you’ll only pay labor, so the cost will range from $600 to $1,500. How long does it take to replace a heat exchanger? About 5-8 hours, so your furnace will be out of use most of a day. Complex jobs might cost $2,000 in labor – or if the job is done on a weekend or evening when labor rates are higher.
Info Tip: Most furnace heat exchangers ARE under warranty. Why? Because major furnace brands offer warranties of 20 years or “Lifetime” on the heat exchanger, even if the other parts only have a 10-year warranty.
By contrast, replacing the entire furnace will run $3,000 to $7,000+ depending on the size, efficiency and performance of the new furnace.
Full cost details are found later in this article.
How Much Does It Cost to Replace a Heat Exchanger?
Here are fuller details about gas furnace heat exchanger replacement cost plus a comparison of heat exchanger repair vs new furnace installation.
If your furnace has a defective heat exchanger, this is where you need to do some serious thinking about the two main options: having the heat exchanger replaced or buying a new furnace.
Under Warranty: If your heat exchanger is still under warranty, you will only need to pay the cost of labor to have it replaced with a new one – usually under $2,000.
Out of Warranty: If your heat exchanger is not covered by a warranty, a new part will cost anywhere from $400 to $3,000 depending on the brand and the size of your furnace, with the average being closer to $900 to $1,200 – just for the part. Add to that the cost of labor, which will usually be $75 to $125 per hour per technician. Figuring 5 to 8 hours for the job, the labor will be $600 to $1,500, bringing your total cost to around $1,000 to $4,500. Again, the average replacement cost is about $2,400.
Should I Buy a New Furnace?
A new furnace in the “mid-efficiency” category (80-89% efficient) will cost anywhere from $3,000 to $7,000 for the furnace plus installation. The average being about $4,800. A “high-efficiency” furnace (90-94% efficient) will cost from 40% to 100% more, or approximately $4,500 to $9,500. About $6,500 is average.
Looking at these numbers, you can see that the average cost of a new furnace installed ranges from slightly less than twice the cost of replacing a defective heat exchanger that is not under warranty ($2,400 vs $4,500) to more than double the cost. If your furnace with the bad heat exchanger is more than 10-12 years old, you might be wise to purchase a new furnace, knowing that it will probably give you more trouble-free years than an older one that has had the heat exchanger replaced.
What About a Secondary Heat Exchanger?
Most high efficiency furnaces that are 90-94% efficient (or even more), achieve that extra efficiency by having a secondary heat exchanger; they are sometimes called “condensing furnaces”.
The secondary heat exchanger captures some of the heat from the hot gasses that normally escapes out the flue after they have heated the primary heat exchanger. This “reclaimed” heat results in you getting more heat from the same amount of fuel. It also means that the gasses going out the flue will be cooler.
These heat exchangers can also become defective and can be replaced. As with the primary heat exchanger, the secondary exchanger will probably have a fairly long warranty period. The cost of installing one will usually be $400 to $600. The price of the unit alone is around $300 to $2,600 depending on the brand.
Heat Exchanger Replacement by Brand
Here are the major brands and their costs to replace a heat exchanger. Note that some brands are identical, so we’ve listed them together. Heat exchanger price for units under warranty and not under warranty are given.
| Brands | Heat Exchanger Replacement Cost Under Warranty | Heat Exchanger Replacement Cost NOT Under Warranty |
|---|---|---|
| Trane & American Standard | $700 – $3,100 | $1,300 – $4,500 |
| Carrier & Bryant | $825 – $2,900 | $1,500 – $4,375 |
| Heil, Day & Night, Tempstar | $525 – $2,750 | $1,300 – $4,000 |
| Rheem & Ruud | $650 – $2,900 | $1,450 – $3,750 |
| Goodman, Amana & Daikin | $600 – $2,800 | $1,250 – $3,500 |
| Lennox | $850 – $3,200 | $1,500 – $4,700 |
| Armstrong Air, AirEase & Ducane | $725 – $2,675 | $1,400 – $3,850 |
| Maytag & Tappan | $850 – $3,100 | $1,600 – $4,250 |
| York, Luxaire, Coleman | $750 – $2,900 | $1,450 – $4,100 |
Should I Replace My Heat Exchanger?
Our recommendation is to put the money into a new furnace, especially if your furnace is 10+ years old and you intend to live in the home for 5 or more years. Your cash is better spent with a new furnace and a fresh warranty.
But let’s back up a bit.
Do You Need a New Heat Exchanger or Furnace?
So, an HVAC technician told you your heat exchanger is cracked, and if you don’t replace it, you could die from carbon monoxide leaking or start your home on fire.
While both are possibilities with a genuinely cracked heat exchanger, telling customers they’ve got a back heat exchanger when they don’t and then trying to sell them an expensive repair or furnace replacement is one of the worst scams in the HVAC industry. We don’t think it is tried very often, but there are scammers out there. A reputable furnace repair technician discusses the scam in this video.
We generally recommend that you have the furnace checked with a meter that shows carbon monoxide in the air coming from the supply line of the furnace. And get a second opinion. Most HVAC technicians are honest; but there are a few bad eggs out there who give the rest of the industry a bad name.
More Research on Heat Exchangers
If you aren’t familiar with gas furnaces and feel you’re not equipped to make a decision about having yours replaced – or buying a new furnace, this information should help.
What is a Heat Exchanger?
In a natural or propane gas or an oil-fired furnace, the heat exchanger is an aluminized steel or stainless steel component that may be shaped like a box, tubes, or a clamshell with several chambers. It is a major part of your furnace, though not very complicated. During a heat cycle of your furnace, the heat exchanger is heated to a high temperature when the flames from the burners are directed inside the individual chambers.
The blower (fan) in your furnace blows room air around the outside of the very hot heat exchanger and sends this now heated air into the ductwork which then goes into the rooms of your home. Normally, there is no connection between the flames or hot gasses from the flames inside the heat exchanger and the air in your home which passes outside the heat exchanger. There’s more information in the Pick HVAC Guide on Heat Exchangers.
What Would Cause a Heat Exchanger to Crack?
Let’s discuss the two most common reasons.
Expansion and contraction over years of heating: During each heat cycle, the heat exchanger is heated extremely hot – perhaps even red hot – in order to sufficiently heat the air to satisfy your room thermostat. When the thermostat is satisfied, the furnace burners shut off, but the blower that pushes the hot air continues to blow until the heat exchanger cools down to something close to room temperature.
This is a good thing, because it serves to utilize as much of the heat created by the burners as possible, meaning a more efficient furnace. But since metal expands when heated and then contracts when cooled, this repeated expanding and contracting of the heat exchanger can eventually result in the metal weakening and cracking.
Impeded airflow: If the super-hot air the furnace is creating can’t be pushed out of the furnace, everything inside it will get too hot. Most furnaces have a high-limit switch that will shut down the furnace if it gets too hot. But if that doesn’t work, the excess heat can cause the heat exchanger to crack.
What would cause impeded air? The number one reason is a dirty air filter. Learn more about this in our guide How to Know When to Change My Air Filter.
What Are the Symptoms of a Cracked Heat Exchanger?
For the most part, there are no specific indications that the homeowner will have if the heat exchanger in the furnace is cracked. The furnace will probably heat just about as well as if everything was OK. One possible symptom is that one or more household members might be having unexplained headaches or nausea caused by carbon monoxide leaking into the air ducts. This might especially affect a family member who spends more time inside the home than the others. Physical symptoms like this should not be ignored! If your furnace has not been inspected by a competent, licensed HVAC technician in several years, this would be a good time to have it done.
How Can I Know If a Heat Exchanger is Cracked?
There are several ways to determine if a heat exchanger is cracked, but some of the tests would have to be done by a trained technician, unless you are quite handy.
Flame Test: This test might be done by a DIY homeowner. With the cover removed from the furnace so you can see the burners, activate the furnace so the burners are firing. Before the blower comes on, you should see blue flames directed into the center of each chamber and perhaps just a small amount of orange flames around the edges. When the blower comes on, watch for any sign of the flames being blown back toward the burners. If there is, this is a sign that there might be a crack in the heat exchanger allowing unwanted air to enter the defective chamber. Yellow flames mixed in with the blue that weren’t there before the blower came on is another possible indication.
Static Pressure Test (Match Test): This involves turning the furnace blower on with the heating system off. In other words, the blower will run, but the burners will not ignite. With the blower running, insert a burning match on a stick or stiff wire into the space directly in front of where each burner would normally be sending its flame. If one or more of the chambers in the heat exchanger has a crack, the flame of a match held at the end of the burner will be distorted or even blown out by air coming backwards out of the exchanger. The test is shown in this video from Lennox.
Camera Test: A technician can insert an infrared camera inside the furnace to view and record the site of a crack in the heat exchanger. This is a test that usually requires the burners or the blower to be removed.
Gas Detector Test: If carbon monoxide is getting into your ductwork, a gas detector should show that. Most furnace technicians will have such a device.
Can You Fix a Cracked Heat Exchanger?
A cracked heat exchanger is never fixed. Sure, welding cracks might work for a while, but the cost to remove/weld/replace would be higher than replacing the heat exchanger. Plus, so much of the metal would be weakened, it just wouldn’t make sense. It’s a question we get, and that’s the short answer.
What About the Warranty on My Heat Exchanger?
Typically, the heat exchanger will have a longer warranty than all the other components of the furnace. Some manufacturers like Goodman and Amana (both Daikin brands) will replace the entire furnace if the heat exchanger fails during its warranty period. Heil, Day & Night and a few other brands are joining Daikin brands in offering furnace replacement if the heat exchanger fails.
Remember: Labor is not usually included, so you will have to pay for that, even though the heat exchanger itself is no cost to the homeowner.
Two things to keep in mind concerning your new furnace warranty:
(1) For the warranty to be in effect, it must be registered with the manufacturer, usually within 60-90 days of installation.
(2) Many furnace warranties require maintaining your furnace to a certain level, which usually involves a professional heating contractor’s ability. The average cost of a professional furnace tune-up is only $100 to $125, which is much cheaper than the cost of a major furnace repair. Be sure to read the owner’s guide when purchasing a new furnace or buying a new home which has a new furnace installed.
