Problems Caused by a Damaged Heat Exchanger

A key component in a gas-powered furnace is the heat exchanger (or heat exchangers if you have a high-efficiency condensing furnace). The name describes its basic function: it exchanges heat with air from the blower in the furnace, moving the heat from the combustion gas to the air and cooling down in the process. The combustion gas never touches the air that reaches your home.

The heat exchanger resembles a metal clamshell. During the heating cycle in the furnace, the chamber traps the combustion gas from the burner, which heats the metal walls (causing the chamber to expand slightly) to transfer to the air. Once the process finishes, the cooled combustion gas has changed into an exhaust vapor, which vents to the outside through the exhaust flue. (In a condensing furnace, it moves to a second heat exchanger, then out the exhaust flue.) A damaged heat exchanger with cracks and leaks is a serious problem in a gas furnace that requires immediate attention from a trained HVAC technician.

Whatever the time of day, you can call Goettl Good Guys Air Conditioning. We’ve cared for Marana, AZ furnaces for decades and are able to put that experience to work for you. 

What are the problems with a damaged heat exchanger?

The #1 issue with a heat exchanger that has developed cracking along it—probably a result of corrosion and the expanding action of the exchanger—is that it permits the escape of exhaust gas. One of the products of burning natural gas is carbon monoxide (CO), which is highly toxic and combustible. You do not want CO leaking into the furnace cabinet, where a small spark could cause it to ignite. Worse, CO could enter the air from the blower and spread into your home, where it’s hard to detect because it is odorless, colorless, and tasteless.

It rarely matters how small the damage to the exchanger appears: when the exchanger heats up during the heating cycle, the metal expands and stretches any small damage wide open.

How can you avoid this danger? First, as a precaution, have CO detectors installed in your house. (Some local codes require homes have them installed.) Second, make sure your furnace receives professional attention once a year from a maintenance technician who can catch potential trouble with an exchanger and replace it. Third, if you notice any corrosion developing on your furnace, shut off the gas and call for repairs right away. Fourth, listen for clicking sounds from the cabinet after the blower turns on; this often warns of a heat exchanger crack.

Damaged heat exchangers are rare as long as a furnace receives regular maintenance and repairs. Make sure you sign up for a maintenance program with Goettl Good Guys Air Conditioning that keeps furnaces in Marana, AZ working safely. You don’t want to leave such an important job to amateurs.