Cleaning and Testing Your Furnace This Winter

Hand Cleaning Grill Plate of Floor Heating Vent in Home

Proper furnace maintenance for your heating system is important for continued reliability, efficiency, and performance throughout the winter season. Thorough cleaning is part of the annual maintenance service for furnaces, which you need to schedule each year, preferably before cold temperatures and foul weather arrives. Often referred to as a tune-up, a technician will inspect electric or gas furnace components, check and adjust their operation, clean dirt from parts, and complete maintenance to keep wear and tear damage at bay.

While professional furnace maintenance helps keep your system clean, you may find that your furnace becomes dirty again over the course of winter. Using your gas furnace heavily during this time results in more opportunities for dust and dirt to cycle through ducts and accumulate within the system. When the furnace needs to be cleaned, its performance may suffer, resulting in poor temperature control inside your house, reduced efficiency accompanied by increased energy bills, and even the potential for damage that requires repair or a replacement part. If you did not have time for an annual tune-up or you notice furnace cleaning is needed once more, you must take action to protect the furnace.

A clean furnace will make for a happy homeowner and a comfortable home, so make sure you keep your heating equipment cleaned throughout heating season. Williams Comfort Air walks you through each step of this project and explains how to clean furnaces safely and correctly, as well as how to test it afterwards.

Why Is It Necessary to Have Your Furnace Cleaned?

As mentioned above, air cycling through the ducts and HVAC system carry dirt and dust into the furnace. Your furnace filter is meant to protect against this and keep those particles out, but each filter is different – not all have the power to remove finer particles or capture as many contaminants, and if the furnace filter itself is dirty, it becomes a burden on the system and is unable to deliver the benefits expected of its use. 

Even if you remove the old one and put in a new replacement filter regularly, you may still notice a dirty furnace – this is because you’re using the heat more often during the cold season, so there are more opportunities for the furnace to become dirty as more frequent air cycles will blow more content into the system.

Dirt and dust in a furnace are problematic for two key reasons:

Once these contaminants clog up your furnace filter, the dirty filter will block air movement through the system and the home. Poor airflow causes comfort issues inside the house, reduced system efficiency, and traps too much heat inside the furnace – overheating can cause the equipment to shut down and may damage parts inside furnaces.
When dirt and dust settle on parts inside of the furnace, the accumulation of this content impacts the performance of the affected part. Buildup may place an undue burden upon a component, forcing it to overwork to compensate, which also causes the furnace to expend more energy. This stress may cause the part to malfunction and need a repair, or break down entirely, requiring replacement of the part. And that’s the good news – what’s worse is that more serious issues could develop inside the furnace, such as a heat exchanger crack that causes carbon monoxide to escape into the house or a total system failure that cannot be fixed.

How Often Should You Have Your Furnace Cleaned?

Furnace cleaning is necessary on an annual basis – at least once per year, and that’s at the minimum. If you find the gas furnace is in need of a cleaning in the middle of winter, you must not put this project off or else you may see an increase in utility costs or even a sign that points to the need for repair in the near future.

How Do I Know if My Furnace Needs to Be Cleaned?

If your system has not been cleaned since your annual tune-up last year, it’s definitely time for a cleaning. However, this schedule isn’t the only sign that you don’t have a clean furnace, Throughout the winter while your heat is in use, watch for a sign such as:

You Notice More Dust in the Home, Even When You Clean Often.
Household Members Experience Increased Allergy Symptoms or Asthma Attacks in the Home.
You Hear a Banging Noise from the Furnace Shortly After It Starts up, Which Is a Sign of Dirty Burners.
You Can See a Layer of Dirt and Dust on Components When You Open the Furnace Access Panel.

How to Clean Inside a Gas Furnace

Professional maintenance encompasses far more than simple furnace cleaning, so you should always make sure to have this service performed by a technician each year. However, keeping a clean furnace between these visits is simple enough for most homeowners to manage on their own. Each step below shares how to clean the important components of your gas furnace.

1. Turn off Power

Before you clean a furnace, cut the electrical and gas power supplies to prevent accidents. Turn off electricity at the breaker in your home electrical panel. Find the gas valve that sits on the gas line that runs into your furnace and close it by turning the handle perpendicular to the pipe.

2. Check the Furnace Filter

Remove and inspect the filter to determine if replacement is necessary as the first step of your furnace cleaning project. If the filter surface is completely clogged with dust and dirt, it’s time for a new one. Hold the filter to a light source to see if any light shines through – if there is no light, replace the filter. If a washable filter is in use, lay the filter on its back with the dirty side up then gently vacuum away debris. Once you have removed as much content as you can with the vacuum, rinse out the remainder with water and let the filter fully dry before you reinsert it.

3. Clean the Blower

The blower is the furnace part that will blow heated air through the ducts and into the living areas around the house. Inside the blower compartment sits the blower motor and fan, which may be linked by a fan belt, or the components may be connected directly.

Remove the metal access panel on the front of the furnace to access the blower chamber, then set the panel aside. Make sure to keep track of any screws you had to remove to take off this panel, as many furnaces will not start up if the panel is not properly reinstalled.
Many furnaces have the fan situated on a track so it will slide out for easy access, though some units have a direct drive blower assembly. Unscrew the control board and remove. It may be necessary to remove wires in order to do so – record their order before disconnecting to make sure you are able to replace the wires properly after cleaning. If the fan is attached inside the compartment by screws, remove them and keep track of them for replacement.
Use a soft brush to dislodge dirt and grime from between the fan blades to clean the blower. An old toothbrush will do the trick.
Use a larger brush to clean the blower motor housing. A paintbrush comes in handy here.
Use a vacuum to clean away all dirt and dust from the blower compartment.
Dampen a cloth with water and wipe down the blower assembly and blower compartment to remove any last bits of content.
Replace all blower parts in order, then replace and secure the access panel over the blower compartment before turning the electricity and gas power supplies back on.

4. Clean Combustion Chamber and Parts

The furnace combustion chamber is where combustion occurs to create the heat that warms the air of a home. Because a gas furnace burns fuel, soot buildup is common in this area of the system – soot buildup can cause corrosion and damage the furnace. Burners and pilot lights can also be affected by this buildup as well as dirt, requiring cleaning.

Turn off the electrical power to your furnace at the switch on its exterior. If you have been using your furnace, give it time to cool before you start the next step of this project.
Remove the access panel to the combustion chamber and keep track of removed screws.
Turn the power switch back on and set the thermostat high enough to activate the burners. Take a look at the flame coming from the burner – you want it to be evenly burning and blue in color. If the burners burn a yellow flame, they are dirty and must be cleaned.
Turn off electrical power and shut the furnace gas valve.
Use a medium-bristled brush to sweep content off each burner and sweep out the combustion chamber as best you can.
Use a straw or compressed air to blow dust and dirt off the pilot light assembly or hot surface ignitor, as well as the flame sensor.
Use a vacuum to further clean off the burners and the combustion chamber, removing all traces of soot and dirt.
If needed, use a cloth to wipe each burner and burner assembly clean.
Replace the access panel to the combustion chamber, then restore gas and electrical power to the furnace.

5. Finishing Touches and Test Your Furnace

Once you have completed the furnace maintenance service needed to clean the inside of the heating system, take a cloth and wipe down the exterior furnace cabinet to remove any dirt or dust. Use water to dampen the cloth if you need to remove caked-on matter.

Lastly, you need to test the furnace out to ensure you have reinstalled all parts correctly.

Verify you have turned the electrical power and gas supply back on.
Make sure the furnace filter is repositioned properly in its chamber.
Set your thermostat’s temperature higher than the current room temperature to trigger a heating cycle.
Take a look inside the combustion chamber to make sure the burners have lit.
Feel for warm air flowing from the vents inside your house.

Final Words

If all was done correctly, your clean furnace will fire up just fine! If you experience troubles after cleaning your furnace and cannot find the cause, contact your technician for assistance. Williams Comfort Air is happy to assist Indianapolis area homeowners with their furnace maintenance needs, including routine cleaning! Whether it’s time for your annual maintenance visit or you need an extra cleaning during winter, give us a call!