What to Do About Furnace Rust

Got furnace rust? What does it mean? Do you need to do anything about it? We’ve got all the answers.

Why Does a Furnace Rust?

Your furnace isn’t like a water heater. It doesn’t use water to heat the home – it uses air. So if you see rust on the outside of your furnace, you’re probably wondering where it’s coming from.

Like all types of heat exchangers, your furnace uses processes like evaporation, condensation, combustion, and convection to heat, cool, and move the air. One of the most popular types of furnace is a condensing furnace. A condensing furnace uses two heat exchangers. The second heat exchanger condenses the water vapor from the hot flue gases. This extracts more heat, making it one of the most efficient furnaces on the market.

Unfortunately, when there’s water, there’s a potential for rust.

What Happens to the Water?

When your furnace is working properly, a tube called the condensation drain line removes any water from your furnace. There are several reasons why your condensate line may be ineffective. If you’ve had a cold winter, you might have a frozen condensate line. The drain or the line can become clogged with algae, dirt, or other residue. A leaky drain pipe can lead to furnace rust over a period of time.

Where Is the Rust?

The furnace rust might not be externally visible. Older heat exchangers can rust over time, but only an HVAC technician would see this. That’s (another!) reason why regular expert maintenance is so important. Too much rust can lead to holes or cracks in the heat exchanger, causing a deadly carbon monoxide leak. If your inspector says there is rust in your heat exchanger, get it taken care of right away!

Rust can be found in unexpected places. If your pilot light won’t stay lit, it could be because the gas jet that lights it has been clogged with rust. In a gas furnace, the burners needed to fuel the heat exchanger can also become encrusted with rust and need cleaning.

What Should You Do?

If you see rust anywhere in or around your furnace, you need to call an experienced HVAC technician. Rust means that water is leaking from somewhere, and your technician has the tools and knowledge to diagnose the problem. Don’t wait on this.

Furnace rust can be a symptom of a larger problem. Rust doesn’t automatically mean an expensive repair bill; you might just have a clogged drain line. Air conditioners are often located above furnaces. An issue with your air conditioner could cause water to drip down onto your furnace. If you notice rust on your furnace, call a technician and so he or she can take a look at the heat exchanger and make sure there aren’t any larger problems.

Rust eats away at metal, so the longer you let the problem go on, the worse it’s going to get. That means more money for repairs or even a total replacement. Even a small amount of rust can be a big problem. If you see rust on your furnace, contact Newcomb and Company today.

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