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Common Causes for Furnace Rust and How to Address Them

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Furnace rust is a common problem that many homeowners face, especially during the winter when the furnace is working at its peak. Rust can seriously harm your furnace, necessitating expensive repairs or possibly replacement. 

This article will discuss some common causes of furnace rust and how to address them.

Cause #1: Humidity

A common cause of furnace rust is high humidity. Humidity can cause the metal components of your furnace to rust over time. This is especially true if your furnace is located in a damp basement or crawl space. 

To address this issue, you can install a dehumidifier in the area where your furnace is located. This will help to reduce the humidity levels and prevent rust from forming in your furnace.

Cause #2: Condensation

Condensation can occur when the warm air from your furnace meets the cooler air in your home. This can cause moisture to form on the metal components of your furnace, which can lead to rust over time. 

To address this issue, you can install a condensate pump or drain line to remove excess moisture from your furnace.

Cause #3: Age

Over time, the metal components of your furnace can begin to wear down and become more susceptible to rust. To address this issue, you may need to replace some of the metal components of your furnace or consider replacing your furnace altogether if it is too old.

Cause #4: Lack of Maintenance

A lack of maintenance can also contribute to furnace rust. If you do not regularly clean and inspect your furnace, it can become dirty and prone to rust. 

To address this issue, you should schedule regular maintenance appointments with a professional HVAC technician. Your furnace can be cleaned and examined by them to make sure it is in good condition and free of rust.

Cause #5: Chemicals

If you store chemicals near your furnace or use harsh cleaning products on it, this can cause the metal components to become corroded and rusted. To address this issue, you should store chemicals away from your furnace and use gentle cleaning products when cleaning your furnace.


Prevention is the best way to avoid furnace rust. By taking proactive measures, you can prevent rust from forming on your furnace in the first place. 

This includes installing a dehumidifier, addressing condensation, scheduling regular maintenance, and being mindful of chemicals. You can ultimately save time, money, and frustration by avoiding furnace rust.

DIY vs. Professional Repairs

If you do notice rust forming on your furnace, it’s important to address it as soon as possible. While some minor rust issues can be addressed with DIY solutions, more serious rust problems may require professional repairs. 

It’s important to know when to call in a professional HVAC technician to address furnace rust to ensure that the repairs are done properly and safely.

Replacement vs. Repair

If your furnace has significant rust damage, you may need to consider whether to repair or replace it. While repairs may be possible in some cases, a severely rusted furnace may be beyond repair. 

In this case, replacing your furnace may be the best option to ensure that your home stays warm and safe during the winter months. A qualified HVAC specialist can assist you in deciding if replacing your furnace is the best option or repairing it.


Furnace rust is a common problem that can cause serious damage to your furnace if left untreated. By understanding the common causes of furnace rust and how to address them, you can prevent rust from forming on your furnace and extend its lifespan. 

Whether you need to install a dehumidifier, address condensation, replace old components, schedule regular maintenance appointments, or be mindful of chemicals, taking action to prevent furnace rust is important for the health and longevity of your furnace.

Do you need reliable furnace maintenance in Whitby? Climate Experts has got you covered! Our team of experts specializes in home heating services, furnace repair, HVAC, and air conditioning repair and maintenance in Pickering, Ajax, Oshawa, Toronto, and the surrounding areas. 

Don’t wait until your furnace breaks down. Contact us now to book your appointment!

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