How to Clean a Natural Gas Furnace

What You'll Need
Clean rag
Flashlight or work light
7/16-inch socket and ratchet
Vacuum with hose attachment
New air filter
1/2 -inch drain line
Drinking straw
Stiff-bristled brush
Emery cloth
Replacement belts
Non-detergent motor oil

It is important to change the air filter in a natural gas furnace, but it is even more important to clean the furnace itself. Dirt, soot and dust can dramatically reduce the efficiency of your furnace and increase heating and maintenance costs and allergens that are suspended in your home's air. To avoid these problems, clean your furnace at least once each year. The best time to do this is in warmer months when you don't need to use your heater. The following are 6 tips that will help you know how to clean your furnace.

Step 1 – Shut Off the Power and Gas

Find your furnace's electrical power switch and turn it to Off. If you can't find this switch, pull the power cord from the power receptacle. If this fails, find your power panel, locate the switch that controls power to your furnace and turn the switch off. Then, locate the valve that controls the flow of natural gas into your furnace and shut off this valve.

Step 2 – Clean the Furnace Exterior and Vacuum the Interior

Using a clean, dust absorbent cloth, wipe off the furnace's exterior surfaces. Then, remove the furnace's access door to gain access to your furnace's interior. If the interior is too dim to see the furnace components, dirt, and dust; use a flashlight or work light, and begin vacuuming. If you are unable to reach the back burner area with the vacuum hose, try attaching a ½-inch drain pipe to your vacuum hose with duct tape. Be sure to remove the blower door and vacuum inside the blower compartment.

Step 3 – Clean the Blower

To clean the blower, first remove any bolts or screws that secure the blower to the furnace frame using a socket wrench and screwdriver. Use a stiff bristle brush and your vacuum to clean off the blower blades. If you can remove the blades, you will be able to better clean them.

Step 4 – Replace the Air Filter

Remove and inspect the air filter. If it is dirty, replace it with a new one.

Step 5 – Clean the Pilot Light, Igniter and Flame Sensor

Remove dust from the pilot light and igniter by blowing through a beverage straw pointed at the pilot light and igniter. Remove the flame sensor by pulling it from the brackets that hold it in place and then use an emery cloth to wipe it clean.

Step 6 – Check and Replace Belts, and Oil Where Needed

Examine furnace belts for damage, cracks, or for excessive slack. If necessary, replace the belts leaving no more than  1 inch of slack when putting the new belt on. For older furnaces, use a non-detergent motor oil and oil the blower bearings and motor shaft.

Step 7 –  Finish

Replace all parts and doors, restore electrical power and gas flow. If the pilot light is out, re-light it.