We want to start off by saying if you hear clicking from your furnace as it cycles on and off, and the sound hasn’t changed since you’ve gotten your furnace, then you might actually be hearing your ductwork shift a bit as the temperature of the air inside of it fluctuates. This is normal, and as long as there is no change and you’re having your furnace professional inspected once a year through maintenance, you have nothing to worry about.
If, however, a new clicking sound has started, or it sounds like it’s coming from another part of the system, then you’re right to be alarmed. This clicking could be coming from a crack on the heat exchanger, and it’s clicking as it contracts back into place when your furnace cycles off and cools down. Why is this a problem? Read on to find out!
About the Furnace Heat Exchanger
Your furnace’s heat exchanger is an essential component. It’s the area where the heat from the combustion gas that your furnace develops is transferred to the air from the blower fan, which moves into and through the ductwork. This combustion gas shouldn’t come into direct contact with the air, otherwise, it opens up your household to carbon monoxide (CO) exposure.
So instead, the combustion gas enters the heat exchanger, a clamshell-shaped metal chamber. The heat of the combustion gases raises the temperature of the metal walls of the heat exchanger, and as air from the blower passes around it, heat is transferred to the air.
Therefore, the heat exchanger is actually what makes it possible for your furnace to heat your home!
The Problem with a Cracked Heat Exchanger
A damaged heat exchanger can allow exhaust fumes to escape from the heat exchanger and leak into the indoor air. The most toxic of these fumes, as we alluded to above, is carbon monoxide (CO), which can cause serious health problems, and has even caused fatalities in homes in severe cases.
When your furnace is properly installed and in good shape, it sends these otherwise potentially harmful fumes out a flue. However, a crack in the heat exchanger can allow these fumes to leak out.
So, what causes this problem?
The most likely culprit is corrosion, which can happen over years and years of system use contributing to wear and tear. The reaction between the combustion gas and the metal of the heat exchanger over time causes the metal to weaken. This said, the problem of a cracked or damaged heat exchanger is a lot more common in an aging system than it is a newer one–but it’s still a problem worth being aware of.
About That Clicking Sound…
As we said above, when a damaged heat exchanger contracts as it cools, you may hear a clicking sound as it settles back into place. These cracks are so small that the average person wouldn’t even be able to see it after the heat exchanger has cooled down. This is why it’s vital that if you do hear it, you give our team a call right away.