How to Clean Gas Furnace?

Your gas furnace has to be cleaned at least once a year to ensure correct functioning.

Before cleaning the furnace, you should turn off the power to the unit and the gas supply. Use a damp rag to clean the exterior and a vacuum and brushes to clean the inside of the furnace; to properly clean the burners and blower you would have to remove them.

Does Gas Furnace Need to Be Cleaned?

If you want your gas furnace to be efficient and have a long lifespan, then you would have to clean it at least once a year (before the beginning of the heating season). However, cleaning the unit twice per year is even better as it will help you keep the furnace in peak condition.

Here are a few signs your gas furnace needs cleaning:

  • Dust and debris – if the furnace is full of hair and grime and the air filter is caked with dirt, then the unit certainly does need a clean.
  • Yellow furnace flames – the flames should be blue, if they are yellow or orange, it means that the burners and flame sensor are dirty.
  • High energy bills – if your heating bills have gotten unusually high, then it looks like the dust buildup inside the furnace is causing it to overwork. 

How Long Does It Take to Clean a Furnace?

It is going to take a professional around 2 hours to clean a gas furnace (a little longer, in case there is a lot of grime).

If you decide to perform the cleaning on your own, you should expect it to take much longer.

The things that should be done during the annual cleaning and check-up include:

  • Examining and cleaning the flue pipes, blower, burners, and heat exchanger
  • Examining and replacing the filters
  • Measuring the gas pressure
  • Checking the operation of all safety controls

How Often Should You Clean Furnace Ducts?

The air ducts should be cleaned every 2-5 years. The frequency depends on a wide range of factors – HVAC use, climate, location, presence or absence of mold, whether there are pets in the household, and so on.

Your furnace ducts need cleaning, if…

  1. You have opened one of the vent covers and the inside contains plenty of debris and dirt
  2. The air registers have dust buildup
  3. The air filter gets clogged more often than usual
  4. The blower motor and fan are covered in dust

Read: Furnace Noise Problems

How to Clean Gas Furnace?

Annual cleaning is especially crucial for combustion systems. Proper and regular cleaning will help make sure that your gas furnace is reliable and efficient.

Can I Clean My Furnace Myself?

Basic cleaning can be performed by anybody. However, you are going to need a little more expertise to properly maintain the internal components.

Fact: professional furnace cleaning will cost you anywhere between $50 and $300.

If you feel comfortable doing the following, then you can certainly try taking care of your gas furnace on your own.

  • Turn off the power and the gas to the furnace.
  • Clean the exterior surfaces with a damp cloth or rag. Remove the furnace access door and the burner cover and carefully vacuum the inside.
  • Remove the blower and clean it with a small brush and vacuum. Do not touch the wiring and the counterweights on the blades.
  • Clean the pilot (igniter) by using a straw and blowing the dust off. Be careful as these parts are extremely gentle.
  • Remove the flame sensor and clean it with a fine emery cloth.
  • Inspect the blower belt for any signs of damage and check the tension.
  • Remove the oil caps and clean them. Oil the bearings by applying 2-3 drops of lubricating oil.
  • Change the air filter.

Read: How Do I Maintain A Furnace Myself?

How Do I Clean the Dust Out of My Furnace?

For the outside of the furnace, you can use a regular vacuum cleaner with a brush attachment

To dust off the electrical connections, use a feather duster.

Is It Safe to Vacuum a Furnace?

Yes, you can use a vacuum to clean your gas furnace.

It is better to choose a model with removable attachments. An upright vacuum with a hose is not the right fit for the job – you’ll be able to clean only the filter.

You can vacuum the outside of the furnace case, the base, and even the inside using a household vacuum or a shop vac with a wand attachment. Use other extensions to get rid of the visible dust.

How Many Times a Year Should You Change Your Furnace Filter?

Ideally, you would want to change the filter every 3 months (or even more frequently, if there is such a need). 

Thick filters can be replaced not as often. On average, a 4-inch filter has to be changed every 6 months and a 5-inch one – every year.

Replace the filter, if…

  • It is visibly dirty
  • The heating system is running more frequently than normal
  • The house has become dustier
  • You have noticed strange smells next to the unit (including a burning smell)

How Do you Clean the Burners on a Gas Furnace?

The burners are cylindrically-shaped parts of the furnace made out of metal and located in the burner box. Their number can vary from two to six.

Warning! You should be extremely careful when cleaning any part of the furnace. If you are not comfortable doing that, then leave the job to a professional.

  • Turn off the power to the furnace and the gas supply.
  • Remove the access panels.
  • Locate the burners (they can be either open or hidden in a metal case) and take a picture of how they are placed in the furnace.
  • Remove the screws that are holding the burners in place and take them out of the furnace.
  • Use a brass brush to scrub the burners. You can then use compressed air to remove any flakes of debris that might be stuck inside.
  • Put the burners back in place.

Read: Why Gas Furnace Is Overheating?

How to Clean Furnace Blower?

The blower’s main job is to blow air through the ducts and into your house. As this part of the system has to deal with a lot of air, no wonder that it can get extremely dusty throughout the years.

  • Turn off the power to the furnace.
  • You might have to remove the capacitor that is located on the side of the blower housing. You would have to remove the wires (it is a job that is suitable only for those who are used to working with wiring).
  • Remove the blower wheel and motor. Mark where exactly the squirrel cage hub sets.
  • It is best to clean the blower wheel with a spray wand that is used in car washes. Don’t apply too much pressure, do not damage or remove the balancers, and don’t touch the fins as they are sharp.
  • Use a soft-bristled brush to clean the fan motor. Lubricate it, if necessary.
  • Reassemble the blower assembly and place it back in the furnace.

Read: Furnace Blower Motor Makes Noise When Starting – Troubleshooting Guide

How to Clean Furnace Heat Exchanger?

If your gas furnace has an efficiency level of 80%, then there is one heat exchanger. If the efficiency is 90% or above, then the furnace has two heat exchangers.

  • Turn off the power and gas to the furnace.
  • Use a wire brush to remove dirt from the heat exchanger block. Loosen any soot from each chamber.
  • Vacuum the block assembly and use a narrow attachment to get deeper into the chambers.

Read: Can You Have A Gas Furnace And Heat Pump?

What Happens If Furnace Burners Are Dirty?

In such a case, the flames won’t be even and of the right height.

This will…

  • Reduce the amount of heat the furnace is able to produce
  • Make the system work much harder than it’s supposed to
  • Increase your heating bills
  • Increase the risk of carbon monoxide poisoning as the flames are not able to burn completely.