Why Your Furnace Is Rusting and What You Can Do About It

December 16, 2021
Furnace Rust in Olathe, KS

Seeing rust on your HVAC unit can be a confusing experience. Your furnace doesn’t use liquid in order to heat your home, so the presence of rust seems impossible. Though rusting isn’t always a serious problem that needs immediate attention, it can morph into that. Seeing rust, whether inside your furnace or on the outside cabinet, is always a reason to give us a call at Mike Bryant Heating & Cooling. Here is how a furnace rusts and what steps you need to take next.

Is Furnace Rusting Common?

Though it may seem a bit strange, a little rusting on your furnace is fairly common. Rust is caused by a unique set of circumstances. When water, metal, and oxygen mix and interact with each other, they start an oxidation process that in turn creates rust.

When your furnace runs, it creates combustible gasses. These gasses contain both oxygen and hydrogen, creating rust over time as they pass over metal system components. This means that unless replaced fairly early on every furnace will eventually begin to rust. Unless your furnace has other problems, the natural process of oxidation will occur slowly enough that you needn’t worry about it. However, the following issues can speed up the rusting process and wreak havoc.

Old Age

All furnaces will rust with age though proper maintenance work will hold this process off as long as possible. If your furnace is creeping up there in age, being 10 or even 15 years old, a small amount of rust is normal. Large amounts indicate more serious problems that need to be looked into, but normal rust from the aging process is nothing that should cause anxiety. However, know that most furnaces begin to lose efficiency after about a decade of use. A replacement may save you money on your heating bills as well as reduce your impact on the environment.

Excess Moisture

An excess in humidity, which is the amount of water vapor in the air, is a known cause of rust in furnaces. Certain areas of the country are more prone than others to high humidity levels as are certain home conditions. An HVAC system that isn’t keeping up with heating or cooling demands, for instance, can leave excess humidity in the air. Water leaks in the home can cause rusting as well, even if you’re not aware of it happening.

Air Conditioner Problems

One potential source of water leaks is your air conditioning system. Every time your air conditioner runs to cool your home, water is used in the process. Assuming that your home has a centralized AC system as opposed to a window unit, it’s integrated directly with the rest of your HVAC system. A leak has the potential to drip right into the ductwork of your HVAC system, raising the humidity in the home and creating a pool of water in a prime rust-causing location.

Exhaust Malfunctions

The exhaust system for your furnace plays an important function in your HVAC system. The exhaust system fans gasses and hot air that are produced by the running of your furnace, blowing them outside so that they don’t circulate around your home. An exhaust system that’s clogged or damaged in some way may trap this excess heat and gas inside the building, especially around the furnace itself. This raises moisture levels in the room and accelerates the rusting process.

Potential Risks of a Rusty Furnace

Rust does nothing but cause more and more damage over time. As rust sets into metal, it begins eating into it. This causes the metal to begin to flake away and disintegrate, destroying the entire heating unit. One of the most dangerous potential consequences of a rusting furnace is damage to the heat exchanger. Cracks in this part of your heating system may cause potentially fatal carbon monoxide leaks, a frightening emergency that it is best to avoid. Aside from heat exchanger damage, any component rust touches can be ruined, making repairs necessary.

The experts at Mike Bryant Heating & Cooling have been proudly providing quality service to the cities of Olathe and Kansas City since 2004. We offer a full range of HVAC services, from heating and air conditioner repairs and installations to geothermal heating, heat pumps, and boiler work. Give us a call today and set up an appointment for us to look at your furnace!

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