How to Clean a Gas Furnace Burner?

DIY gas furnace maintenance saves money on hiring someone to do it – and on gas bills, since it will maximize efficiency.

And it extends the life of the furnace.

Knowing how to clean a gas furnace burner – and doing it – will keep your furnace running at peak efficiency too.

Read on for step-by-step furnace burner cleaning tips. But first, a bit of general information to be sure we’re on the same page.

What is a Gas Furnace Burner?

Your furnace has a gas valve that opens once the draft motor has cleared the vent and sensors indicate the gases can be safely vented from the furnace.

The gas valve or valves release the gas into tubes or ports, and a hot surface igniter (HIS) ignites the gas. The flame sensor senses that the burners are firing, and the blower motor comes on to start circulating air over the heat exchanger through which the combustion gases are passing as they exit the furnace and your house. Heat from those gases is transferred into the circulating air via the heat exchanger.

The assembly or group of parts responsible for the gas release and fire is known as the furnace burner or burners. Like all parts of any heating and cooling system, it is very important to properly maintain furnace burners.

How Often Do Furnace Burners Need to be Cleaned?

Your gas furnace burner should be cleaned once a year if your climate is cold and your furnace gets used from fall into spring. In the warmest climates where furnaces are a “once-in-a-while” thing, every 5+ years is often enough. Most of the country falls in between, and homeowners where winters are moderate to fairly cold should clean furnace burners every 2-3 years as part of a general cleaning and HVAC tune up.

You can do this yourself or hire a local heating and air conditioning company for the work.  A normal yearly cleaning and maintenance visit by a HVAC technician will generally cost between $125 and $250 based on what is done. Cleaning your gas furnace burners is something that can definitely be done by a handy, do-it-yourself individual.

Read your warranty: Most furnace warranties state that the manufacturer can deny warranty claims if the furnace isn’t professionally maintained once per year. The maintenance would include cleaning the gas furnace burners. However, in our experience, manufacturers rarely deny claims based on furnace maintenance alone (though they deny plenty of claims for other reasons). Still, if you want to follow the furnace maintenance guidelines from Trane, Lennox, Carrier, Bryant, Goodman, etc., annual furnace maintenance that includes burner cleaning is on the checklist.

What Happens if Furnace Burners are Dirty?

Dirty burners – so what?

Dirty burners reduce furnace efficiency. They smoke and smell when really dirty. The accumulated dirt can absorb moisture and cause rust/corrosion of the parts. If the gas valve gums up with dirt, it might not release sufficient gas for your furnace to burn cleanly and produce enough heat to make your home as warm as you’d like it to be.

Furnace burner clogs that impede proper burning can happen after the furnace hasn’t been used in a long period of time, like over summer or if the home has been vacant for a while.

Step by Step Directions on How to Clean a Gas Furnace Burner

OK, with those preliminaries covered, let’s discuss how to clean a furnace burner.

In order to completely clean the gas furnace burners, you will need a few necessary tools and supplies to complete the task:

  • Phillips screwdriver
  • Steel wool (fine)
  • Socket wrench with sockets
  • Brass wire brush
  • Air compressor or a can of compressed air

Once you have all the tools and materials to clean your gas furnace burner, follow these steps:

  1. Turn off the power to your furnace - You can do this by turning off the switch or turning off the furnace breaker at the main panel. Electricians recommend that you use the breaker box to fully ensure that the power is off. Next, find the furnace’s main gas supply valve and turn it off.
  2. Take a picture - Using a camera or your smart phone, take a picture of the burner assembly. This will be used for reference when you are putting everything back together.
  3. Remove the burner retaining plate - Using your Phillips screwdriver, remove the screws on the retaining plate to the combustion chamber. Most often, there will be two screws, but there may be three or four. Be sure that you place the screws in a place you won’t lose them.
  4. Remove the burners - Furnace burners are cylindrical and look similar to an automobile’s exhaust pipe. Begin with the burner that is located closest to the gas valve. Using your hand, gently push it forward to release the latch connecting it to the combustion chamber, and then remove it. Take care, as the burners can be fragile. Any damage to the burners will result in the need to replace it. Also, make sure you know what direction the burner goes back in. It is easy to not put them back correctly, so take your time and be careful.
  5. Clean each burner - Using the brass wire brush, scrub the buildup closest to the combustion chamber. Next, use your air compressor or compressed air and blow the air through the other end to loosen any carbon deposits located inside the burner. Then brush the burner to remove all the deposits. Continue until all the carbon deposits have been removed. Make sure that you also blow away any debris that is on the fins of the burner.
  6. Clean the flame sensor - A flame sensor is a small rod that is often covered with porcelain at the base. It is located behind the last burner, and the flame sensor often gets coated with carbon. Use steel wool to clean the flame sensor, and then reconnect it.
  7. Replace the burners - Begin with the burner that is the farthest away from the gas valve, then replace each burner in order by fitting one end into the proper place on the gas supply and lowering the other end until the burner is horizontal, and the tabs are in place.
  8. Replace the retaining plate - This is an easy step. Put the retainer back over the burners and fasten it with the proper screws.
  9. Test the furnace - Do a blue-flame test by turning on both the gas and electric to your furnace, crank up the thermostat, and observe the color of the flame when the furnace turns on. If the flame has yellow or orange streaks, contact an HVAC technician. The yellow and/or orange streaks indicate combustion problems such as a leaking heat exchanger, something that can lead to carbon monoxide leaking into the air circulating in your home. It might also represent the need to make a simple adjustment to the air/gas mixture.

Alternate Method for Cleaning a Furnace Burner

If you are struggling to remove the furnace burners or if the whole process seems a little daunting, there is a way to clean them without having to fully remove them. You can use compressed air or an air compressor to blow air through the burners. Next, use a brush, like a bottle brush, to clean the insides of each burner. Finally, clean the blower fins, the blower motor, replace the filter, and use a mild detergent to clean the heat exchanger. Make sure any moisture is dried up before putting the cover back on the furnace.

Watch it Done

It’s often useful to see someone else do the job we’re about to tackle. This video is from a handy homeowner shows how to clean a furnace burner using the tools and methods explained above.

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