How to Fix a Furnace That Is Blowing Black Soot

eHow may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here.
A small amount of soot is normal for many furnaces.
Image Credit: Jupiterimages/Comstock/Getty Images

Excessive soot production is a common complaint among furnace owners. Oil burning equipment is more prone to this problem, but it can occur with gas burners as well. A little cleaning and troubleshooting may resolve the issue, but in many cases you may need the assistance of a technician to eliminate soot problems in your furnace.

Advertisement

Step 1

Switch to a higher quality fuel. Low grade fuels create more soot when burned, especially if you have an oil furnace, and you may be able to reduce your furnace's soot production simply by using a higher grade of fuel.

Video of the Day

Step 2

Clean or replace your furnace filters. A clogged filter makes your furnace run less efficiently than it should, which in some cases may lead to increased soot production.

Advertisement

Step 3

Clean your furnace. A small amount of soot production is normal, but over time it can build up and give the impression that your furnace is producing more soot than it really is. Perform a thorough cleaning of all accessible parts of your furnace, including the flue, chimney and duct work, with a chimney-cleaning brush or contact a professional.

Advertisement

Step 4

Run your furnace, after cleaning it, to see if any soot reappears. A small amount of soot immediately after a cleaning is normal; but if soot continues to build up, you may have a more serious problem.

Step 5

Contact a licensed HVAC technician to have your furnace inspected and serviced if the appliance still produces large amounts of soot. There may be an issue with the unit's burner, heat exchanger, fan limit switch, barometric damper or another component.

Tip

All furnaces vary in terms of design and manufacture so do not attempt to take apart your furnace unless you have the user's manual handy.

Warning

Make sure your furnace is completely turned off and has had time to cool down before you attempt any cleaning or repairs.

Advertisement

references

Report an Issue

screenshot of the current page

Screenshot loading...