How to Clean Your Furnace for Winter: Best Practices

Professional Services
January 25, 2022

If you are wondering how to clean your furnace for winter, you might be glad to know that Professional Services hears this question frequently. As West Bend's trusted HVAC company, we like to emphasize that a furnace is a vital investment that requires consistent maintenance, but there are quite a few ways to prepare it for Wisconsin’s harsh winters.


Below, Professional Services provides a simple method for keeping the furnace clean so that you can avoid breakdowns, extend the unit’s longevity, and heat any size home more efficiently.


A Note on Why Cleaning The Furnace is Important

Before our team delves into the step-by-step process for safely cleaning a gas furnace, it is helpful to look at how proper maintenance benefits a furnace. For example, cleaning a furnace at least once a year is typically enough, but this changes with the furnace’s age, repair history, energy efficiency, and overall condition. Getting stuck without a working furnace in the middle of a Wisconsin cold spell is not an option, and a basic cleaning session could prevent a major headache in the dead of winter. 


Cleaning the furnace:


  • extends its life
  • prevents costly breakdowns and emergency repairs
  • removes dust and debris from moving parts and ail filters
  • stops clogging inside the furnace
  • improves efficiency and heat distribution
  • saves money on monthly energy bills


The right cleaning tools and techniques are crucial for safe maintenance, and skipping professional cleaning sessions is never a good idea. Without maintenance, a furnace is likely to overheat, shut off completely, or produce harmful carbon monoxide. Rather, entrust the unit to teams like Professional Services for consistent results.


Six Best Practices for Gas Furnace Cleaning from Professional Services


1. Turn Off the Power First

A furnace is a high-voltage unit that may use gas or oil for fuel. The combination creates plenty of room for accidents, so the first step in learning how to clean your furnace for winter is turning off the unit’s main power source. You will also need to switch off the fuel source to prevent an explosion.


  • Locate the breaker panel.
  • Turn off the power supply to the furnace and the on-off switch.
  • Turn off the gas shut-off on the inline gas pipe (the shut-off valve for oil will be near the tank).


2. Clean the Combustion Chamber

The combustion chamber is where the furnace’s fuel combusts to create heat. This area will typically have soot from gas combustion; extreme cases include corrosion. Dirt is also typical of air ducts and filters that are due for a clean.


  • After turning off the power and fuel line, remove the combustion chamber panel.
  • Turn the power back on to test. If the flame burns yellow, the fuel isn’t burning evenly.
  • Turn the power off.
  • Sweep the soot and loose debris out of the chamber.
  • Use a vacuum for dust from dirty burners and pilot lights, or use a cloth.


Don’t forget to replace the access door.


3. Clean Out the Blower

The blower moves the heated air from the furnace through the ducts and vents. Moving parts include the blower motor, belts, and fan. 


  • Remove the door to the blower and check for holes from corrosion.
  • Next, remove the control board and wires to access the fan. Take a picture of original configurations for easy restoration later.
  • Then, clean the fan using a toothbrush or other small, soft-bristle brush.


The final check is to locate the blower motor housing and use a bigger brush to remove dust from these parts. Vacuum all other particles from the blower compartment and replace the components using the photograph.


4. Check the Furnace Filters

Learning how to clean your furnace for winter includes handling the furnace filters, which capture dirt, pet hair, dust, and other contaminants. A high-end furnace filter will last longer and trap more particles; some are even washable. It is best to replace or clean the filter every few months during the cold season. 


  • Pull out the furnace air filter. If it’s severely clogged, there will not be light poking through it. A completely clogged filter needs replacement, while a washable filter needs washing and drying.
  • Vacuum or wipe debris from the air filter. If your filter is washable, rinse out the leftover debris and only install it once it is completely dry.


Oil furnaces feature an oil filter that also needs regular maintenance—a yearly replacement from Professional Services is sufficient.


5. Check the Oil Motor and Blower Bearings

Older furnaces have motor and blower bearings that facilitate fan movement. These parts need annual oiling to keep the moving parts in good condition. A squeaking sound coming from the furnace is a helpful indication that it needs maintenance. 


  • Locate the motor and blower bearings in the blower compartment.
  • Wipe off the residue on the caps.
  • Take off the caps and lubricate the bearings with a few drops of machine oil
  • Remember to replace the clean caps and tighten them.


6. Test the Furnace

Cleaning the furnace’s exterior is the final step of the process.


  • Wipe it with a damp cloth to remove dust and stubborn particles.
  • Then, restore the electrical power and gas or oil.


It is also important to test the furnace to ensure the correct installation of the filter and thermostat activation. The burners in the combustion chamber should light properly, and there should be no cold air blowing out of the vents around the home. The cleaning session is complete if:


  • the blower does not squeak,
  • the air warms, and
  • burners light properly.


Otherwise, you may need a team like Professional Services to diagnose a deeper problem.


Affordable Winter Furnace Cleaning by Professional Services


Are you interested in learning more about cleaning a furnace or preventing your HVAC unit from freezing? The professional HVAC repair technicians at Professional Services make yearly furnace maintenance and cleaning easy and affordable. Our technicians have over 30 years of in-field expertise, and we cover all of Port Washington, WI, and the surrounding communities. 


Professional Services’ best practices for furnace cleaning are not exhaustive, but it is a great start for exploring how to clean your furnace for winter—call us at (262) 218-2636 today to learn more.

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