Does An Electric Furnace Have A Filter?

Any forced air furnace should have a filter. Not all furnaces and duct systems will have a filter in the same place. Some of the common places for a filter to be located are:

1. In the return grille on the ceiling or on a wall.
2. In the duct next to the furnace.
3. Inside the door of the furnace.

Locating your filter is a process of starting at the return grille and working your way to the fan or blower in the furnace. Or, if you want to start at the furnace and go the other direction, go for it.

The return grille is the one large grille usually located in the center of your home or high in the ceiling. It’s where the air from inside your home enters the system.

Return grilles are fairly common in sizes of 20 X 20 or 20 X 25 inches. Although various sizes are used to accommodate construction types and areas that may be taller or narrower on walls.

There can also be more than one return grille. Some high end systems have a return grille each room which is ideal to provide the changes of air in individual rooms that commonly have the doors shut.

HVAC systems that have a common return in a central location of the home rely on the gap under the door to allow air to leave the room when the door is shut so the air can return to the furnace through the return grille.

In some homes, mostly manufactured, you may have noticed a grille just above the door to each room. This grill is for that return air or the air supplied to the room to find it’s way back to the furnace.

Do You Have One Or More Return Air Filter Grilles?

Just take a gander around the house. Look on the walls and the ceiling. They would be the larger of any grilles that you see. In order to tell if it’s a filter grille or not you may need a flash light to have a look inside the grille.

Filter grilles or grilles intended to hold a filter will have either a couple of tabs to pull down or knobs to unscrew.

If you don’t see any type of latch then you simply have a grille not intended to hold a filter and your filter is somewhere else, hopefully.

These filter grilles are an easy replacement of a standard grille. Sometimes you may need to do a little trimming or framing, but it’s well worth the improvement to have the whole duct system filtered.

Next Options To Locate The Filter

Looking at the furnace it’s important to differentiate between the return ducting and the supply ducts. Electric furnaces have a lot of versatility. They can be installed with the air blowing up, down or sideways. This next image shows a heat pump coil with an electric furnace. If you don’t have a heat pump just ignore the heat pump coil section in the image.

The filter in this photo is behind a narrow slot there indicated by the arrow and the filter was very difficult to remove and put back into place.

The installer even plumbed the PVC drain right in front of the filter access which made it necessary to bend the filter to R&R the thing.

Filters have to be before the furnace. Between the blower and the return grille

Check Out The Return Duct Near The Furnace

Installers can be a little sneaky when installing filters in a return duct. Probably not intentionally, but field fabrication comes in many different shapes and sizes.

Look for a strip of metal with some screws or a slide of some type that may resemble a patch or a door. This is where you are going to have to really poke around. Hopefully this is not what you will find. The filter was allowed to become packed with dust and debris and got sucked into the duct. Notice the filter laying at the bottom of the duct.

It’s that lump of fiberglass framed by flimsy cardboard down in the abyss of the return duct. The customer would eventually go to change the filter and it was never there. So he would just add another filter thinking the filter fairy kept removing them.

Maybe My Filter Is In The Furnace?

I hope not, but it’s better than nothing. Manufactures put filter slots in there furnaces because they know some installers will be too cheap or lazy to install something better.

This is a great example of just stick a filter somewhere. No support to keep the filter from being sucked up and opening the system to blow by of dust and dog hair. Cat hair too, didn’t want to discriminate.

It’s those furnaces where the filter is crammed in between the fan motor and the side of the furnace where the return duct is cut in. By the time you fight the filter out of the compartment you’ve shaken half the dirt off into the fan compartment to be sucked up into the system next time the blower comes on.

Generally that slot in a furnace is for a 1″ filter that is somewhere around 16″ X 20″ by dimension. Most homeowners use those cheap flimsy fiberglass filters that you can pour salt through.

Or, in an effort to stop more dust they get one of those high efficiency pleated filters and unbeknownst to them the temperature rise across the furnace goes up because they are a resistance to air flow.

With the rise of temperature difference certain parts of the furnace fail, like elements and limits.

You can learn a bunch more on this subject by reading an article I wrote that specifically addresses types of filters. Titled “What Filter Should I Use In My Furnace“. What an imagination I have.

What Kind Of Filter Should I Have And Where Should It Be Located?

I can tell you what I like. I can show your where it should be located, but doing that project may require some alterations and a professional. I would never dis an enthusiastic DIY’er so don’t be put off by that statement.

This could very easily be tackled depending on how your current system is constructed. Take a look at one of my jobs. Look how easy the filter is located, removed and replaced. A simple magnetic door and a very high quality filter.

The return air duct is the one on the left. The airflow into the furnace is the same as the arrow that indicates the filter. The filter is easy peasy lemon squezzy to change.

Whenever I can make these fit I use a 4″ Honeywell filter can. It’s there F100 and it comes in enough different sizes to fit most any application. Check it out at on Amazon

This type of filter container has a 5″ (approx) filter. The filters are constructed with pleats. The pleats give the filter more square inches of filtering material. With more square inches of material you can use a denser fabric to catch the dust.

Filters are generally rated in what called a MERV rating. MERV being an acronym for “Minimum Efficiency Reporting Value”. THe higer the MERV rating the more dust bunnies the filter can catch.

Furnace filters will be changed more often when they are east to locate and remove. Your equipment will last longer and you will be putting money in the bank.