Instructions for Cleaning and Testing Your Furnace This Winter

Annual furnace maintenance isn’t just a recommendation – it’s a requirement if you want your heating system to remain safe, functional, and reliable all winter long. During the winter months, your furnace works hard to distribute warm air throughout your home, and over time, dirt and dust can clog filters, enter into your furnace, and accumulate on everything from fans and burners to delicate parts within the housing, such as sensors and ignitors that control the release of gas within your heater and other essential operations.

Fortunately, professional furnace cleaning is designed to eliminate dirt from within your furnace, care for equipment maintenance needs, and to screen for problems that could hamper the efficiency of your system. During routine tune-ups, HVAC professionals will inspect, check and adjust essential parts within your furnace, looking for issues like clogged ducts and cracked heat exchangers that could leak carbon monoxide into your home. These routine service calls should be performed at the start of the heating season, preferably in the fall.

However, since your furnace can become dirty between service calls, you may want to try some furnace maintenance of your own to keep your system clean and functional. Routine cleaning can help your heater last longer and reduce energy consumption, which could lower your overall cost of ownership. A clean furnace also paves the way for a more comfortable home, since your system will be able to heat efficiently and distribute warmed air throughout your house.

Thomas & Galbraith Heating, Cooling & Plumbing wants every homeowner to feel capable when it’s time to clean the heating system – follow our convenient step-by-step guide to furnace cleaning at home. Remember, anytime you need furnace maintenance, our entire team is a call away to make sure you have the service you need to keep your home safe and comfortable.

Why Is Furnace Cleaning so Important?

Your HVAC system is designed and balanced to heat air and circulate it throughout your home. Designed with air returns, your HVAC system pulls cold air through return ducts, into a heating chamber, and then redistributes warmed air throughout your home, pushing heat into the rooms across the house. To keep your furnace tidy, heating systems are designed with a filtration compartment fitted with a filter.

Filters range significantly in design and efficiency, with higher MERV ratings indicating their ability to trap finer particles and do so more effectively. However, regardless of the size or variety of the filter, screens that become dirty allow dirt to blow into the furnace and collect on components. Dirty furnaces can be very problematic for these two simple reasons:

  1. Halted airflow: When furnace filters become dirty and clogged, air has a more difficult time moving through the furnace. In addition to creating uneven heating, clogged filters can also drive up energy consumption, since the system will have to expend more energy to move and warm air. Poor airflow caused by dirty filters can also trap hot air inside your system and cause overheating, which can shut down your system and damage parts.
  2. Dirty system components: Dirt and grime can also stress the delicate components of your furnace, resulting in a malfunctioning part or damaged system. For instance, if certain sensors don’t trip because they are covered in dust and dirt, the system may not start or shut down when it should and could overheat. This issue could lead to the need for a minor repair or cause a serious issue such as a crack in your heat exchanger, which creates an opportunity for carbon monoxide to leak into your home. In addition to posing very real dangers for your family, this common problem can also be expensive to fix, since it may create the need for a furnace replacement.

How Frequently Should Furnaces Be Cleaned? 

Conventional gas furnaces should be cleaned annually, ideally before the start of the winter season. However, it’s never too late to have your furnace cleaned if you suspect grime and dust within your system. During the winter, furnaces can become dirty fast, since many families spend more time indoors and air continuously recirculates. It may be necessary to clean the furnace yourself in between furnace maintenance appointments.

What Are the Signs My Furnace Needs to Be Cleaned?

Think back to the last time you had your furnace tuned up and deep cleaned. If it has been at least a year, it’s time to schedule a service call for maintenance and cleaning. However, you may need another cleaning in between visits if you spot any of these common signs that indicate a dirty furnace:

  • Excess dust at home: Anytime you notice more dust at home between cleanings, you may need to have your furnace deep cleaned. Air may be picking up dust and dirt from the furnace as it circulates, moving it back into living areas within the house.

  • Breathing problems: If members of your household experience frequent allergy or asthma attacks, your furnace may be dirty, causing increased exposure to their triggers.

  • Furnace noises: Banging noises, when the furnace starts up, could signal dirty burners that cause delayed combustion.

  • Visible dirt and grime: If you can see visible dust accumulation inside your furnace, you should clean your furnace.

Steps for Cleaning a Gas Furnace

For many, it’s easier to hire a professional HVAC contractor to deep clean the furnace. However, if you have a system that gets grimy easily, or you are proactive and love home maintenance, you can clean your furnace on your own. Here are a few steps for cleaning a gas furnace properly. Remember that if you become overwhelmed at any point along the way, we are here to help.

1. Cut the Power 

Never attempt to clean or service a furnace that is connected to electric power and gas. Turn off the electrical supply to the furnace by flipping the breaker on the corresponding panel within your electrical box. When your system power is off, you shouldn’t see any working lights inside the unit. After you locate the gas valve that supplies your furnace, turn it perpendicular to the pipe to stop the flow of gas into your system.

2. Switch out Your Furnace Filter

Find the furnace filter compartment within your heater and open the door to access the air filter if applicable. If the filter looks visibly dirty or covered with dust, replace it. If you aren’t sure whether or not it’s time for a new filter, hold the screen up to a light to see if brightness shines through. If the filter is clogged enough to stop light from shining through, you need a new filter. Throw away disposable filters and replace the filter with one that is the same size. Make sure to insert the filter in the same orientation.

If you use disposable air filters, vacuum the surface to remove any built-up dirt and dust before rinsing the filter clean with water. Leave the filter out to dry completely before reinserting the filter.

3. Clean the Blower Unit

Your furnace’s blower unit is the component that physically pushes air into your home. Your furnace has a blower compartment that includes the blower motor and fan. Here are steps for cleaning these parts.

  1. Access the blower chamber by removing the metal access panel. Keep any screws you remove in a safe place, since your furnace may not turn on if the panel is not replaced and secured appropriately when you are finished.
  2. The blower fan may be fixed to a track allowing the unit to slide out. However, if your furnace utilizes a direct-drive blower assembly, you may need to unscrew the control board to remove it. Since you may also have to disconnect wires during this step, take a photo of the inner workings of the blower compartment before you disconnect anything, so you’ll know what it’s supposed to look like once reassembled. If the fan is screwed into place, remove the screws carefully and keep them in a separate place from the access blower panel screws.
  3. Using a soft brush, gently brush away dirt from the fan blades to clean the blower. Old, soft-bristled toothbrushes are ideal cleaning tools for blower fans.
  4. Use a larger brush with soft bristles, such as a clean and dry paintbrush, to clean the blower motor housing.
  5. Vacuum up any dislodged dirt from inside the blower compartment.
  6. Wipe down the blower assembly and compartment with a damp cloth to remove any additional debris.
  7. After the chamber is clean and dry, replace all of the blower components in the reverse order you disassembled them in. Secure the blower compartment door before restoring gas and power.

4. Clean the Combustion Compartment 

Gas furnaces burn gas to heat the air inside your home – its combustion takes place within a very controlled environment. Inside your furnace, your system burns fuel within the combustion compartment to generate heat. However, anytime fuel is combusted, soot can form. Over time, soot buildup in this area can corrode components inside your furnace, such as pilot lights and burners, which is why this chamber needs to be carefully cleaned. Follow these steps to remove soot as well as dirt and dust that makes its way inside.

  1. Cut power to your furnace by flipping the switch on the exterior of the heater body. The system will need time to cool off before you attempt to clean the combustion chamber.
  2. Remove the metal access panel. Keep the screws in a safe place.
  3. Turn the power to the furnace back on and set the thermostat high enough that it would trigger the system to heat. Watch the burner flame. If the flame is blue and burns evenly, your system is clean. If the flame is yellow, the burners are dirty and need to be cleaned.
  4. If the burner needs to be cleaned, turn off electrical power again.
  5. Use a clean, dry, medium-bristled paintbrush to sweep out the combustion chamber.
  6. Blow out the inside of the combustion chamber with a can of compressed air. If you have an air compressor, you can also use the air gun attachment to generate the stream of air you need to blow out the component. Use the air to dust off the flame sensor, the pilot light assembly, and the surface ignitor.
  7. Vacuum out the combustion chamber to remove any additional dirt and soot.
  8. If vacuuming doesn’t remove all traces of soot, use a clean microfiber cloth to wipe each burner clean.
  9. Replace the combustion chamber access panel before restoring gas flow and power.

5. Cleaning Up and Testing Your Furnace 

Before you finish the job, it’s a good idea to wipe down the exterior furnace cabinet to remove any last traces of grime. Only use water and a damp cloth, since some cleaners are flammable. It’s also smart to double-check that you have reinstalled all of the components properly before moving ahead with home heating. Check these things before switching your furnace back on.

  1. Double-check that the electrical breaker has been switched back on, and that the gas supply is open. The valve should run in line with the pipe when it is open.
  2. Make sure there is an air filter inside the filtration compartment. Double-check to make sure the arrow on the filter is pointing the same direction airflow will travel.
  3. Turn your thermostat up to trigger a heating cycle. This makes ensuring your furnace is working properly fast and easy.
  4. Look inside your combustion chamber to see if the burners have lit.
  5. Feel air coming out of the vents in your home to ensure warm air is filling your house.

In Summary… 

When you are finished cleaning the inside of your furnace, the system should turn on and fire up right away. However, if you experience any setbacks when you turn on your heater, we are here to help. Thomas & Galbraith Heating, Cooling & Plumbing keeps a dedicated crew on hand 24/7/365 for heating emergencies, since trouble with your furnace can be dangerous. Whether you experience a heat outage or you can’t get your system to turn back on, we are here to help. Let us know if you need to schedule your annual furnace maintenance, or give us a call at the first sign of trouble.

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