How to Clean a Natural Gas Furnace

Modern natural gas furnaces often can burn at more than 90 percent efficiency, but even the most energy-efficient furnace won't heat a home efficiently if it's covered in built-up dirt, grime and soot. Cleaning the furnace each year before it gets cold ensures that it's operating at its best, keeps home-heating costs down and will make breathing easier for allergy sufferers in the home. While once a year is enough for the full cleaning, change filters much more often, preferably once a month.

Things You'll Need

• Clean rag
• Screwdriver
• 7/16-inch socket and ratchet
• Vacuum with hose attachment
• 1/2-inch drain line
• Drinking straw
• Stiff-bristled brush
• Emery cloth
• Replacement belts
• Non-detergent motor oil

Instructions

Cleaning and Maintenance

1. Turn the furnace off and turn the valve a quarter turn to shut off the gas. Wipe down all the surfaces of the furnace with a clean rag.

2. Using the hose attachment, vacuum around the burners and the base at the furnace. Taping a half-inch drain line to the vacuum hose can help reach the back of the burners. Take off the blower door and vacuum inside the blower compartment.

3. Using a screwdriver and the socket and racket, unscrew the screws and bolts around the blower to remove it. Clean the blades in the blower with a vacuum and stiff-bristled brush. Take out the blades for cleaning if possible.

4. Remove and replace the furnace filter.

5. Use a small drinking straw to blow any dust off the pilot. Also use the straw to blow the dust off the hot surface igniter.

6. Pull the flame sensor from its holding brackets. Wipe it clean with an emery cloth.

7. Check any belts in the furnace for loosening, cracking or other visible damage. Replace any damaged belts, making sure to leave a little less than an inch of slack on the new belts.

8. If the furnace is an older model, oil it's motor shaft and blower bearings with a non-detergent motor oil. Newer models will not have these features.

9. Replace all parts, close all doors and turn back on the power and gas. Check the pilot light to see if it needs relighting.

Tips & Warnings

• Frequent filter changes reduce debris build-up in the blower.

• Even with an annual cleaning, have the furnace inspected once a year for leaks to make sure it is not leaking carbon monoxide into the home. Do not disturb the counterweights on blower blades while cleaning them.

References

• Reader's Digest Fall Furnace Maintenance Guide, Sam Satterwhite

Resources

• Diagram of a Gas Furnace