How to Clean a Furnace? | Tools and Materials for Cleaning a Furnace


We’re at that time of the year when you have your home furnace/heating system blasting at high temperatures. While the temperatures are plummeting outside, your trusted HVAC system keeps things heated in the apartment. Now, that’s great but is your HVAC system working efficiently? No? When was the last time you tuned it up? Or do you even know how to clean a furnace and get it ready for the winter?

Cleaning and maintaining your furnace is crucial to keeping it in good condition and blasting all winter long. Neglecting to do proper tuning for your furnace with the correct cleaning methods may inconvenience you down the line. You don’t want your HVAC burning out one winter evening and leaving out in the cold. It’s time to clean the furnace and prep it to mint working condition.

But then again, it’s not only during the winter season that you need to clean your furnace. So if you notice that your apartment is constantly getting dusty and dirty faster than you can clean it, you should check your furnace. The heating system is probably due for a good wipe-down. And even if the HVAC system’s not the cause of the dust-bunny boom, you’ll still have a clean furnace by the end of the day.

Tools and Materials for Cleaning a Furnace

Basic furnace cleaning and maintenance activities help prolong the life of your heating system plus its efficiency. Interestingly, the entire process of tuning up a heating system is relatively straightforward. You can efficiently complete DIY furnace maintenance if you have the right equipment. That said, let’s take a quick look at the primary materials you need to clean your furnace.

The primary tools you need to clean most furnaces include:

  • Vacuum
  • Brushes (Toothbrush and Scrub brushes)
  • Cotton swabs
  • Toothpicks
  • Rags
  • Replacement filters (for those who use disposable filters)

Of course, depending on the design of your home furnace, you may require other specific tools. However, the essential tools for your home heating system should not vary very much from the ones listed above.

And as you get more comfortable cleaning your HVAC system, you may find some other tools to do the job better. The tools listed above are simply a starting point on what you’ll need to clean your furnace.

Alright then, let’s move to the important stuff — how to clean a Furnace. Keep following.

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Furnace Maintenance Guide

You should pay proper attention to three primary parts of the furnace when cleaning it. Each of these parts has specific steps for its maintenance activities. Therefore, you must know how to clean each of these parts effectively if you hope to extend the life of your furnace and prevent expensive repairs. That said, let’s look at each of these parts and the steps for cleaning them.

The Filter

Since it’s pretty much the job of the filter to trap dirt and dust going in and out, it’s often the dirtiest part of the furnace. In other words, the filter is the main part of the furnace that requires constant cleaning. But if you use disposable filters, you don’t need to bother cleaning this part; simply switch the dirty filter for a new one. However, if you use other filter types, below are the steps to clean them.

Find the access panel outside the surface.

You first want to locate the access panel between the blower system and the duct below the return-air duct. You’ll then find the filter behind the front panel of the furnace. However, to get to the filter, you’ll need to unscrew the front panel from the furnace and detach it from the hooks holding it in place. In some furnace designs, the filter may have an access door, too; you will need to breach this door to get to the filter in this case.

In any case, as you proceed to get to work on the HVAC, ensure to turn off the heating system before you set to work on it. Neglecting to do so is dangerous to yourself and the furnace.

Remove the filter from the tracks.

For most furnaces, the filter should come out quite easily. However, you may have to pull the filter up and out of the tracks to remove it in some situations. In any case, you want to avoid being forceful as you try to remove the filter. If the filter feels stuck, look around for anything blocking the tracks and get rid of them. Don’t try to force the filter out; doing that can damage the tracks and the filter.

Remove The Filter From The Tracks

Inspect the filter for damages

Ideally, you want to go straight to cleaning the filter after removing it from a furnace. However, you need to inspect the filter for damage to decide whether to clean it or replace it. Cleaning a damaged filter is a waste of time and effort since you can’t continue using it. So it’s better to be sure your furnace filter is in good condition before cleaning it.

Go on to clean your good filter by first picking out any loose particles. Then use a mild soap to wash out the filter and rinse with tap water. Dry the filter and ensure it’s devoid of liquid before reinstalling it in the furnace.

If you’re replacing your filter, don’t just buy any filter; take the old filter to an appliance store and purchase a replica of it for a replacement. Also, make sure to wipe the track and the filter compartment clean to get rid of extra dirt. Simply pass a wet towel over the track to get rid of the excess dust.

Replace the clean/new filter

Push the filter back into the furnace and ensure it fits securely in the tracks. If it doesn’t, check for any debris responsible for the obstruction. If you have a new filter that doesn’t work, ensure it’s the right model and size for the furnace. Once the filter is secure in place, close the access door and screw on the panel door.

The Blower Assembly

The blower assembly is the second part of your furnace you want to pay special attention to in your furnace cleaning checklist. The blower is the mechanism that helps to distribute and circulate the heat from the furnace.

The blower assembly pulls in air through the back of the furnace using the mechanism of the fan unit. While pulling in the air, this part tends to attract a lot of dirt and dust. You don’t want it to push the same dust and dirt out through the vent into your living space. That said, let’s look at the best way to clean this part of a furnace and others too.

Disconnect the furnace from all power sources.

The blower assembly is an electrical component of the furnace. Therefore, you want to take extreme care to remove all connections to any power source. By power sources, we mean electrical outlets and battery backup systems. Failure to sever all connections to electrical units may lead to electrocution or other undesirable results.

Unscrew the front panel of the furnace.

You’ll have to remove the whole front panel of the furnace to access the blower assembly. The front panel is the only way to get to the blower unit of a furnace and clean it. Fortunately, removing the panel is as simple as unbolting many screws and detaching the panel from its supporting hinges.

Gently take out the fan unit.

The fan unit does the bulk of the work of the blower assembly. The fan is held in place by a track which prevents it from moving around in the blower compartment. To take out the fan, simply slide it out through the side of the compartment. The fan may be secured in place by bolts. In this case, you’ll need a screwdriver to detach the fan.

The fan should have a bunch of wires connected to it; take extra care to avoid disconnecting the wires by mistake. If you have to disconnect the wires, wrap a little tape around each wire and label them. This will make reassembly easier. Don’t forget to remove the tapes before attaching the wires back to the fan.

Clean the blower compartment

After removing the fan, wash the blower assembly using mild soap or ordinary water. You may use a toothbrush to scrub the crevices of the track and the fan blades. You can also run a handheld vacuum over the unit to completely remove all dust and dirt from the blower assembly. Set the vacuum on low power while moving it over the fan, belts and blades

Reassemble the blower unit and put it back in the furnace

After making sure the blower unit is clean and dry, slide the fan back into the compartment and make sure it fits on the track. Reattach all disconnected wires to their proper ports. MaEnsureke sure to reconnect the backup battery system and plug the furnace back into its power source.

The Heat Exchanger Block

The heat exchanger literally transfers the heat created in the combustion changer to the furnace’s exterior. The blower then takes the work from there, blowing it through the ductwork and into the house. Therefore, you want to pay particular attention to this component as you clean out a furnace. If you have dust and dirt blocking the heat exchanger duct, it will reduce the unit’s efficiency.

It’s easier to clean the heat exchanger block than all the other furnace components. You can quickly do that in the following steps.

  • Turn off the furnace. As with all the previous furnace cleaning procedures, you first want to turn off the unit and disconnect it from all power sources. If you have a gas furnace, please turn the gas off.
  • Brush off dirt stuck to the block. Use a brush to scrub off the dirt build-up on the chambers of the block. You may also use a damp cloth for this task. However, wet clothes may not be sufficient, in which case you’ll need the brush.
  • Vacuum the chambers of the heat exchanger block. Use a narrow vacuum attachment to thoroughly clean all the heat exchanger block chambers. The vacuum will eliminate the dust and dirt you loosened with the brush.
  • Finally, remember to put the furnace back the way it was. Plug it back into its power/fuel sources and ensure everything is working appropriately.

A dirty furnace will not use fuel as efficiently as a clean one. So if your electric furnace is dirty, it’ll consume higher units of electricity than usual. The same principle applies to gas-fueled furnaces.

Therefore, you should endeavour to clean your furnace regularly. Ideally, you should clean a furnace towards the end of fall or at the beginning of winter. After that, continue to clean it at least once a month during heavy-use months (December to February).

Heat Exchanger Block

Other Important Furnace Care Activities

We have covered the basics of how to do a furnace cleaning and activities to keep your heating system in an excellent working condition. But while those may be sufficient to keep your HVAC system running, you need to do more to significantly extend the furnace’s lifespan.

Check and Clean the Flame Sensor

The flame sensor occasionally gathers up residues on its surface, and it can prevent your furnace from igniting. To avoid this, pull the flame sensor out of its bracket when cleaning and lightly wipe the surface with a cloth. Then, put the flame sensor back in its bracket, and you’re good to go.

You can also check if the flame sensor is in good working condition. Hook it up to the multimeter and ignite the furnace to start a heat cycle. Check the multimeter reading. Ideally, it should be between 1.5 to 4uA. Anything outside this range will lead to inefficiency. But to be sure, check the manufacturer manual to confirm the acceptable ratings specified by the manufacturer.

Pull and Clean the Burners

Like the flame sensors, burners rarely ever require cleaning, but they may also be subject to contamination every once in a while. The contaminant is usually dust but can sometimes be rust or soot, leading to misalignment. So, the next time you clean a furnace, try to inspect the burners and make sure they’re free from debris.

If you discover soot or rust on the burners, use a stiff-bristle brush to clean it off the burner’s surface. Then, blow out the burner vestibule area using dry nitrogen or pressurized air. Of course, all these only apply if you use a gas-fuelled furnace. A blocked-up burner can cause carbon monoxide contamination, so don’t ignore the rust on the furnace burners.

Check for Gas Leaks

Again, this only applies to gas-fuelled furnaces. Ensure to check for gas leaks whenever you clean a furnace. This is not only important to preserve the furnace, but it’s also to prevent fire accidents and resource wastage.

You can use soap bubbles or an electronic leak detector to check for a gas leak. However, keep in mind that an electronic detector may produce a false positive when in contact with some pipe brands. Soap bubbles are a cheaper alternative and can provide good results too.

Oil the Motor Bearings

Most old furnace models have two blower-shaft bearings and two motor bearings. You should oil both sets at least once per year to keep them functioning properly,

To oil the bearings, first, use a cloth to clean the caps on the bearings. After that, remove the caps and apply some drops of machine oil to each bearing. Be careful not to add too much oil and make a mess of it; two or drops are enough. Put the caps back on the bearing and return them to their original position when you’re done.

Know When To Call In the Pros

While furnace cleaning and maintenance is pretty much straightforward, there will be times when it’ll be beyond you. There will be situations when your heating system will need a professional touch. At such times don’t hesitate to call in the cavalry. By cavalry, we mean HVAC technicians to come and help you take care of your furnace.

Ideally, you want to contact furnace repair services when you notice irregularities like excessive soot, short cycling and irregular flaming. If your furnace also gives off rumbling sounds and you can’t figure out why you should get a technician to check it out. Lastly, if you discover any development you don’t understand in your heating system, call the attention of the professionals to it ASAP!

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Basic furnace maintenance activities are tasks you can easily handle. It will only take you little effort to clean out a furnace if you have the right resources and motivation. That said, spare no efforts in ensuring your HVAC system is functioning at max efficiency. Clean out that furnace ASAP!

Then again, if you decide you can’t clean out a furnace by yourself, you can call us for help. Our professional furnace repair and maintenance service at ALP Heating can handle the comprehensive cleaning of your heating system. Contact us today!

ALP Heating is committed to providing the finest service possible to important areas. We are delighted to be your go-to cooling and heating business for all of your requirements. Because of our commitment to perfection.