Why Does My Furnace Have Rust and How to Remove It?

Rust on your furnace can be a concerning sight. It might appear on the exterior, inside the cabinet or on the internal components. While furnaces don’t use water to generate heat like boilers, rust can still form.

Corrosion is one thing a professional heating repair technician checks for during routine maintenance. However, there are ways to address a rusty furnace on your own.

Why Does Rust Form on Furnaces?

Moisture is the main culprit for rusty metal surfaces. Although the furnace doesn’t use water, it is exposed to moisture when combustion gases cool in the heat exchanger and form water vapor. This water vapor flows out through the drain line in a well-functioning furnace. In a faulty system, vapor moisture settles on surfaces in the furnace and accelerates corrosion.

When you notice rust outside the heater, cease operation immediately, as it can indicate major internal issues. Rust occurs on the heater due to:

• Air leaks in the furnace or ductwork: Poorly sealed ductwork or furnace components can let in moist air, leading to rust.
• Humidity and water leaks: High humidity levels and leaks from nearby plumbing or a faulty humidifier can cause rust over time.
• Issues with the furnace exhaust: Improper ventilation can trap moisture inside the furnace, accelerating rust formation.
• Clogged drain line: A blocked drain line means that the moisture formed during gas combustion will not leave the system, leading to moisture exposure, a catalyst for rust.
• Aging system: A furnace that has been running for over 15 years is more prone to rust due to prolonged exposure to combustion. It is wiser to replace these old systems, as they are significantly less efficient than newer, more energy-efficient models.

Regardless of how the rust forms, it will result in low energy output efficiency and drain your wallet with utility bills. Our heating repair experts conduct inspections to reveal why you have rust buildup and determine the best course of action to prevent further losses.

Is Rust Dangerous?

Yes, a rusty furnace can bring several risks. Rust can clog the burner jets, diminishing their effectiveness and increasing fuel consumption. Inefficient burning increases carbon monoxide release into your home, which can be dangerous for you and your loved ones.

A rusted heat exchanger presents a risk of cracking, causing deadly combustion gases like carbon monoxide to infiltrate your home. Rust can also affect your fuel supply lines, creating a hazardous situation that can lead to fire or explosion. Over time, rust can weaken metal components, potentially warranting costly repairs or replacements.

How Long Does It Take for Rust to Form?

Under the right conditions, such as persistent humidity or leaks, rust can develop in as little as a few months. Regular inspections can help catch rust early before it causes significant damage.

How to Prevent Rust on a Furnace

Rigorously maintain your annual heater inspection schedule and have issues repaired as soon as you notice them. A professional HVAC technician can help you decide when a system is too damaged to repair and replace it with a newer, more efficient model.

Here are some rust prevention tips for furnaces:

• Ensure proper waterproofing and humidification: Instead of letting water in and then attempting to dry the air with the furnace, you can get a humidifier to keep humidity levels at a controllable level. This helps prevent rust from forming. Humidifiers add moisture to the home during winter months when forced-air systems are running. This also keeps smells and allergens at bay. It is far more cost-effective than combating rust later.
• Check the kick panels: Kick panels are metal plates attached to the furnace unit directly above where it meets the floor. They are exposed to moisture, so rust is likely to form here. These panels will have to be replaced periodically, which is best done by a professional furnace technician.
• Replace the furnace filters and clean them regularly: You can also prevent corrosion with routine filter replacement and regular cleaning of your furnace filters. If air can’t get through the filter properly, moisture may accumulate inside the unit and cause rust to form.
• Schedule AC maintenance and clear the condensate drain line: This is an easy way to prevent rust formation. If the drain line that carries condensation away from inside your AC unit is clogged, water will pool within it and rust your compressor over time. Scheduling for annual maintenance will help avoid costly repairs in the future.
• Call for professional HVAC service: No matter the season, call for professional HVAC service in Central Pennsylvania when you notice rust on your system. After all, if water or humidity is causing this corrosion, it will only worsen over time and cause significant damage to your home. Be sure to inspect and clean other components in your furnace regularly to ensure reliable operation and minimize the risk of rust.

How to Remove Rust From Your Furnace

If you discover rust, it’s crucial to address it promptly. If left alone, rust will continue growing and become more expensive and difficult to fix. Luckily, if you catch corrosion early enough, it can be removed without too much effort or expense.

Here are the best practices for rust removal:

• Light rust: You can gently clean small rust spots with a wire brush or sandpaper and apply a rust-inhibiting primer.
• Severe rust: If your furnace has extensive rust damage, it’s best to contact a professional HVAC technician to assess the damage and repair or replace the affected parts.

Contact HB Home Service Team for Heating Repair and Maintenance

Rust on your furnace is not just unsightly — it can lead to significant efficiency and safety issues. Understanding why rust forms and taking proactive steps to prevent it can extend the life of your furnace and ensure a safe, warm home. Regular maintenance and professional inspections are your best defenses against rust.

If your furnace has severe rust, you can get emergency repair and maintenance right away. We provide furnace repair and maintenance services for your specific needs, allowing you to feel confident in your heating system’s safety. We also offer clean air and plumbing services. Contact HB Home Service Team (PA) to schedule service and maintenance today.