Here's How to Clean and Test Your Furnace for Winter

Hand Cleaning Grill Plate of Floor Heating Vent in Home

All appliances require routine maintenance, and your furnace is no exception. As it works diligently to warm your home all winter long, your heating system will accumulate dust, dirt, and grime, which is why deep cleaning is so important. While routine furnace filter replacement is essential to keep your furnace in top condition, routine professional tune ups can help to remove dirt from parts and sensors, improving heating system performance, efficiency, and indoor air quality.

During professional tune ups, HVAC contractors will conduct essential annual maintenance service. They inspect sensors, fans, ducts, ignitors, burners, and other components of your furnace, such as blower motor ball bearings and fan belts. Damaged components may require repair or replacement parts, and any element that isn’t working at its best will be carefully calibrated and adjusted to ensure maximum efficiency.

Furnace maintenance tune ups should be completed before winter, ideally in the fall. Conventional furnaces require one annual tune up, while heat pumps should be serviced once in the fall to prepare the system for heating, and once in the spring to pave the way for efficient cooling. While it can be difficult to make time for an essential furnace cleaning and tune up, homeowners must make this task a priority to protect their furnace—and their family. Clean, functional furnaces keep your home comfortable, clean, and safe, since they are less likely to emit dangerous carbon monoxide.

Here at Jarboe’s Plumbing, Heating & Cooling, we are committed to helping homeowners live better by making furnace maintenance simple. Follow this easy-to-use guide to learn each step of how to clean dirt and test your gas furnace.

Why Does Your Furnace Need to Be Cleaned?

Your furnace is designed to heat air and circulate air through a complex, carefully balanced heating system. As air is pulled in through returns and moved across the heat exchanger, it is gently warmed and redistributed throughout your home. However, homes are hardly sterile, and dust, dirt, dander, cooking fumes, and even cleaning overspray can pollute your indoor air.

Furnaces are made with an air filtration compartment to screen these fine particulates, and when they are clean and sized appropriately, they work well to keep your furnace—and your indoor air—clean. However, if filters become dirty, contaminants can enter into the furnace housing, collect on components, and spell trouble for your system. Even the most stalwart filter replacers may discover a dirty furnace from time to time, since no filter is perfect. Routine cleanings are necessary to keep your system as tidy and functional as possible. Here are a few reasons dust and dirt can cause problems for your furnace.

  1. Blocked airflow: When contaminants collect on your furnace filter, they eventually block airflow of you do not change the filter with a replacement, trapping too much heat inside your furnace. When your furnace overheats, your system may temporarily shut down or the issue could lead to short cycling. Restricted air movement significantly hampers energy efficiency, since your furnace is forced to consume more fuel as it struggles to warm your home.
  2. Dust accumulation on components: The internal components of your furnace are designed to perform many essential functions. When dirt and grime collect on surfaces, sensors, switches, and other parts can malfunction or experience restricted performance which forces your furnace to work harder than it should to compensate. In addition to consuming additional energy, the stress dirt and dust place on the system can even contribute to problems such as a cracked heat exchanger that can leak CO2 into your home.

When Should You Have Your Furnace Cleaned?

Your furnace should be professionally cleaned annually every fall. However, if you have missed your yearly tune up, it’s never too late for a cleaning. Since families spend more time inside during the winter, and the air in your home recirculates several times a day, having your system deep cleaned can help you to ward off heating and efficiency problems. Your furnace may become dirty due to heavy use, requiring a cleaning mid-season, which you can likely do yourself – but if you’re not comfortable, always call your technician for help.

Does My Furnace Need to Be Deep Cleaned?

Anytime your furnace has gone longer than a year between tune ups and deep cleanings, it’s time to schedule a service call. However, these other signs could signal the need for a thorough internal furnace cleaning in between your regularly scheduled furnace maintenance visits:

  • More dust at home: If it seems like you dust frequently but can’t get to the bottom of the mess, your furnace and ducts may be recirculating grime for you. A deep cleaning could help you keep your home cleaner.
  • Upper respiratory trouble: Excess dust can also aggravate allergies and asthma. Pay attention to how people are feeling, and have your system deep cleaned to rule out any continuously recirculating dust.
  • New noises: If furnaces generate a banging noise shortly after starting up, the burners may be too dirty to ignite properly.
  • Grimy furnace interior: If you can see visible dirt and grime when you remove the furnace access panels, your system needs to be cleaned.

Step-By-Step Guide for Cleaning the Interior of a Gas Furnace

Professional HVAC technicians are best suited for maintaining a furnace, since there are delicate components that could be damaged by mishandling. However, you can maintain a clean, healthy furnace by carefully following these steps.

1. Switch Off All Power to Your Furnace

Anytime you clean or service your furnace, you need to make sure the system is completely disconnected from gas and power supplies. Shut down your furnace by turning off the breaker located on your home’s electrical panel. Find the gas valve that supplies your furnace and turn the valve until it is perpendicular to the line. The valve is open when it runs parallel to the line, so make sure it is closed firmly before proceeding.

2. Check and Replace the Air Filter

After you have your furnace switched off, it’s a good idea to check and replace the air filter. Air filters should be visibly clean. If you open the compartment where your air filter is located, and the entire surface is covered with dust and grime, it’s time for a new air filter. Disposable air filters should be checked every few weeks and may need to be replaced once a month during winter, since people spend more time inside with recirculated air.

Double-check filters by holding them up to a light source, such as a window during the day. If you can see light through the filter, it’s still clean enough to filter air effectively. If the light doesn’t shine through, you need to replace the filter.

If you use reusable, washable filters, start cleaning the surface by vacuuming away dirt and grime. Wash the surface of the filter with clean water, and place the filter on a dry towel to allow it to fully dry before placing it back into the furnace compartment.

3. Cleaning the Blower Component

Furnaces rely on a blower motor and fan to push warmed air through the air ducts and into your home. Each furnace contains a compartment that houses the fan and blower motor, along with the fan belt that connects the two. Here are instructions for cleaning this essential component.

  1. Remove the access panel: Locate the blower chamber and remove the metal access panel. Keep any screws you remove together and in a place you will remember. It may be helpful to place screws in a plastic bag labeled as “access panel.”
  2. Access the fan: Some furnaces may have the fan fixed to a track that slides in and out of the compartment for easy cleaning. However, if your system uses a direct drive blower assembly, you may need to unscrew the control board to access it. Keep these screws separate, together, and labeled as with the screws in step 1. Since you may need to disconnect wires before cleaning the blower assembly, take a photo of the system before you remove them so you know how to reconnect each one once finished with the cleaning project.
  3. Clean the blower: Use an old, soft-bristled toothbrush to clean dirt and grime away from between the blower fan.
  4. Clean the housing: Use a large, clean, and dry paintbrush to remove dust and grime, and clean the blower motor housing.
  5. Vacuum up extra dirt: Vacuum out the entire interior of the furnace blower chamber to remove any dust or dirt that fell during cleaning.
  6. Wipe down compartment: Using a microfiber cloth dampened with clean water, wipe down the blower assembly compartment.
  7. Replace parts and restore power: When you are finished, replace all blower assembly components. Be sure to secure the access panel firmly, or your furnace may not turn back on. Restore gas flow and power.

4. Clean Within the Combustion Chamber

Your furnace uses combustion to heat the air inside your home. Your furnace has a combustion chamber where it burns fuel. Unfortunately, combustion creates soot, and this grime can corrode internal components and build up upon burners and pilot lights if it is allowed to sit in the same place for long enough. Here are steps for cleaning this essential chamber:

  1. Turn off your furnace by flipping the switch on the exterior of the unit. Since your furnace generates heat, give it time to cool down before attempting to clean the combustion chamber.
  2. Unscrew the access panel covering the combustion chamber.
  3. Turn the power back on to the furnace and turn the setting on the thermostat up enough to trigger the furnace to switch on. Watch the flame emanating from the burner. It should burn evenly and be a blue color. If the burners create a yellow flame, the burners is dirty and need to be cleaned.
  4. Turn off the breaker that powers your furnace and turn the gas valve perpendicular to the pipe to turn it off.
  5. Use a soft paintbrush to carefully sweep material off of each burner.
  6. Use an air compressor fitted with nozzle or a can of compressed air to blow dust out of the pilot light assembly or off of the hot surface ignitor (depending on the type of ignition system within your furnace) and flame sensors.
  7. Vacuum out the combustion chamber to remove traces of dirt and soot from the burners and surrounding areas.
  8. Wipe the entire interior clean with a cloth to remove any lingering dirt, dust, and soot.
  9. Replace the metal access panel and secure it tightly with the removed screws. Restore gas and power to the furnace.

5. Double Checking Your Furnace and Testing the System

After the inside of your furnace is clean, tidy up the exterior by wiping the cabinet down with a damp washcloth. This step removes dirt and dust that could be sucked back into your system. Never use cleaners other than plain water, since some products are flammable. Before you turn your system back on, check these elements to make sure the parts were replaced properly.

  1. Check to make sure you’ve restored gas flow and the power supply.
  2. Check to see if the filter is positioned appropriately. The arrow on the filter should face in the direction air will travel into your system.
  3. Turn your thermostat up to trigger a heating cycle.
  4. Watch the flames within the combustion chamber to make sure they are lighting.
  5. Make sure warm air is coming from the vents within your home.

Final Thoughts on Furnace Cleaning

If you cleaned your furnace properly, your system should start right up. However, if your system fails to ignite, makes strange noises, or doesn’t seem to be warming your home, contact us right away for help. Here at Jarboe’s Plumbing, Heating & Cooling, we are always on hand in Louisville, KY for fast, efficient help. Give us a call today to schedule your next cleaning.

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