3 Common Causes of Rust on a Furnace

Since furnaces do not use water as part of their heating cycle, people don’t expect them to develop rust or corrosion. However, furnaces can rust, and when it happens it either indicates a need for repairs or that it’s time to replace the whole unit. We’ll examine why rust occurs on a furnace and what you should do about it.

Quality Air Heating and Air Conditioning can help you when rust becomes problematic for your furnace. If you need repairs or a new furnace installation in Columbus, OH you can trust our years of experience and our NATE-certified technicians to bring you quality service.

Why Furnaces Rust:

• Humidity and moisture: Your furnace may not use water to create heat, but water can still come in contact with it through the return air ducts. During humid weather or after rain, water moisture inside the ventilation system can enter into the furnace and start the chemical reaction with metal that results in rust. This problem will grow worse if your ducts have breaks in them that draw in humid air from other parts of the house. Call for repairs right away when you see rust anywhere on your furnace.
• Leaking air conditioner: In most HVAC set-ups in homes, the air conditioner unit sits above the furnace so both units can use the same blower. Air conditioners create water condensation, which drains away from a condensate pan. If the drain becomes clogged, the condensate pan will overflow and force water to drip onto the furnace and create rust. This situation calls for repairs for both the furnace and the air conditioner.
• Combustion gas reaction: With a gas furnace, the combustion gas in the heat exchanger turns into a liquid vapor as it cools down in the heat cycle. The reaction of this vapor with the metal on the furnace can cause rust, although proper ventilation of the exhaust will prevent it. If your furnace has ventilation problems, rust is often a sign of the problem. However, years of combustion gas exposure will eventually cause rust, so if you have a furnace that has been in operation for over 20 years, the appearance of rust usually means you should have a new furnace installed.

Repair or Replace?

Always consider the age of your furnace when you debate whether or not you should have repairs or just schedule new furnace installation in Columbus, OH. For younger furnaces that have received regular maintenance, repairs are usually the answer. An older furnace may require replacement. Contact an HVAC professional for an informed opinion on your best course of action.

Our excellent technicians at Quality Air Heating and Air Conditioning are available 24 hours a day when you need emergency service on your furnace. We can also help you select, size, and install an excellent replacement furnace if necessary.