Practical Guide on How to Clean a Furnace

Your furnace is part of the most expensive system in your home, and regular maintenance goes a long way towards preventing major malfunction and expensive repairs. Since preventative maintenance is less expensive than repairs and replacements, we put together a furnace cleaning guide and advice for when to hire a Pro.

Before we Get Into the Guide

3 Major Advantages of Cleaning Your Furnace

Improve Efficiency
Spending less money on energy consumption is a top priority these days. A yearly cleaning is important when clean furnaces run better and use less energy.

Longer Lifespan
A buildup of dirt and debris makes a furnace work harder. When the furnace has to work harder, components will wear out quicker. Furnace maintenance is a small investment that will pay for itself by maximizing the lifespan of your equipment.

Clean Air
A dirty furnace will push dirty air around your home. A clean system is capable of purifying the air — protecting you and your family for harmful pollutants that trigger allergy and asthma symptoms.

How often should I clean my furnace?

The furnace is the only thing between you and the bitter cold, and it benefits from an inspection and maintenance routine prior to the arrival of cooler weather.

How often should I clean it: Yearly, in the summer or early fall.

Important to know:

Clogged filters are the #1 cause of furnace failure, and the easiest way to improve indoor air quality and maximize energy efficiency.

Furnace filters need to be inspected and replaced more frequently. How often is a matter of your lifestyle, respiratory issues, if pets are in the home, and the type of filters being used. Filterbuy’s pleated air filters last for 3 months, but there are times when you should change more often.

Use our quiz to get the ideal filter replacement schedule and filter MERV rating for your home.

Filter Type and Replacement Quiz

How and Why to Vacuum Your Furnace

Step 1 - Turn Off the Power and Gas

Never attempt to clean the furnace when the power is still on. If the furnace uses natural gas, turn off the gas as well. Remember, the person who cut the power and gas flow is the only person to turn them back on.

Step 2 - Clean the Outside of the Furnace

It’s best to clean the outside of the furnace and surrounding area first. An ordinary vacuum with a brush attachment will do the trick. However, do not vacuum electrical components. Use a duster in those areas.

Step 3 - Remove the Panel to Clean the Blower

Access the burner and blower motor by removing the side panel. Vacuum every bit of dust off the burners and the furnace base. It can be difficult to reach the back of the burner with your vacuum attachments. If this is the case, tape a plastic tube to the vacuum which gives you a way to reach every nook and cranny.

Make note if you find soot or black powder along the way. This is often an indication of poor combustion.

Step 4 - Remove the Blower to Clean it

Remove the blower motor in order to clean it. Clean the fan blades with a small brush and vacuum. Make sure not to damage the wiring or disturb the counterweights on the fan blade. If you choose to clean the blower fan, make sure you get it all. If you don’t, you could throw off the balancing of the fan.

Step 5 - Inspect and Clean the Heat Exchanger

Look for signs of wear, cracks, and corrosions.

Step 6 - Dust Off the Pilot

The pilot is responsible for igniting the gas like the pilot on a gas grill. Dust it off to make sure it functions properly.

Step 7 - Switch Your Dampers

If your unit provides both AC and heat, it could have dampers that need seasonal adjustments. If so, switch it over to “winter”.

Step 8 - Replace the Furnace Filter

The final step of the furnace cleaning process is to change the filter. If you have a fiberglass filter, consider a high-efficiency pleated filter. Fiberglass only lasts for 1 month when pleated filters perform for 3 months.

Related Maintenance

Clean Your Air Ducts
Air ducts become lined with pounds of dust, dust mites, allergens, pet dander and bacteria. A professional cleaning will reestablish healthy indoor air quality and create a healthier home.

Schedule an air duct cleaning when dust buildup is visible, after the purchase of a new home, or after a remodeling project where dust from building material is suspended in the air.

When to Hire a Professional

Most furnace maintenance can be handled by homeowners, yet it still makes sense to hire a professional at the right time. Here are a few reasons to give your HVAC service tech a call:

Extra Soot: Soot is an indication the burners need adjustment or the heat exchange is failing. If you notice soot or black dust during the cleaning, call your service tech before the heating season begins.

A Yellow Flame: The flame should be entirely blue. If it’s yellow, call a pro. This is a sign of worn-out burners or a cracked heat exchanger.

Short Cycling: Does your furnace shut off too quickly? Yes? That’s a short cycle. This issue requires a pro because there are a few reasons why your unit is shutting down early.