If you’ve read gas furnace reviews on this site, you know that most furnaces come with a lifetime limited heat exchanger warranty. Heat exchangers are crafted from heavy-gauge steel, either aluminized steel or stainless steel most often. In addition, they are usually made from a single piece of steel – there are no welds that can come apart. Heat exchangers rarely fail.
Why Heat Exchangers Fail
When they do go bad, it is almost always a crack. When metal heats up, it expands. When it cools down, it shrinks. If you listen carefully, you can sometimes hear your sheet metal ductwork doing this during a heating cycle. At times, over thousands of heating cycles, the metal heat exchanger will crack. Sometimes they rust. Water is a byproduct of combustion and so heat exchangers are crafted from rust-resistant metals. When they do fail, it usually means, in automobile language, that the furnace is totaled.
How Much Does it Cost to Replace a Furnace Heat Exchanger?
Plenty! The most costly part of replacing a heat exchanger is the labor. That’s the primary reason it is rarely done. For most furnaces, the part itself is under lifetime warranty – or 20-year warranty on some models. The part is covered, but since most furnaces come with a 1-year labor warranty and most homeowners don’t buy extended coverage, the cost of labor must be paid.
Replacing a heat exchanger involves disassembling much of the furnace. It is right at the core of the unit. It’s an 8-10 hour job for most teams of HVAC technicians. When you factor in the cost of labor for most heating and air conditioning companies, it gets expensive. Labor rates vary, but most are between $75 and $125. Total cost can be in the $600 to $1200 range for replacing a heat exchanger.
Repair or Replace the Furnace?
If you’ve got a furnace less than 10 years old, and it’s a high-performance model – high efficiency, staged heating, variable-speed blower – it may be worth repairing. Get estimates on both the repair and the replacement and weigh your options. Have a qualified contractor inspect the furnace and make a professional recommendation. Get 2 recommendations/estimates if you’ve got the time. It might be worth it to replace the heat exchanger.
However, if your high-quality furnace is more than 10 years old – and the older it gets – replacing it starts to make more sense. If the furnace is a basic model to begin with, the cost of the repair may approach or exceed the purchase price. In that case, no decent furnace professional would recommend repairing it. Your money is much better spent on a new furnace.
Beating the Repair Issue
There are a couple of furnaces we’ve reviewed that offer furnace replacement on heat exchangers. Most of Goodman’s furnaces, most of Amana’s models, and a few of the Rheem models offer furnace replacement for a bad heat exchanger. Goodman and Rheem offer it for 10 years, though the heat exchangers are covered for life. Amana offers a lifetime furnace replacement warranty on the heat exchanger for some furnaces. See, for example, the Amana AMVM96 and AMVC95, the Amana ACVM96 and the Amana AMVC8/ADVC8 furnaces. For Goodman, start with the Goodman GME95, Goodman GMH95, Goodman GCH95, and the Goodman GMH8/GDH8. The Rheem Classic Series 90 Plus RGRM is one of the Rheem’s with a 10-year furnace replacement warranty on the heat exchanger.
In most cases, your heat exchanger won’t fail. If it does, the $600 to $1200 bill should give you reason to consider replacing the entire furnace. Perhaps the information here will help you make your decision easier.