Do all furnaces have filters?

Question

I cannot find a filter or even a place to put one in our furnace. The house was built in the 70s, but the HVAC inspector said that the furnace was 12 years old. Maybe it never had one? Maybe it was removed? The previous homeowner heated the house primarily with the fireplace, and we wouldn't be surprised if they modified the furnace. How can I figure out if there ever was a place for a filter? How would we go about adding a filter?

Answer 1

I have never seen a furnace that does not have a filter. It is possible that the filter was removed and all that remains is a couple of slots where the filter had been installed. It is also possible that the filter is / was located on the plenum, just outside of the furnace proper. In this case you should be able to see a slot cut in the plenum where the filter would slide into.

Also, some furnaces use a re-usable mesh that wraps around a wire frame. It is possible the frame was removed and not re-installed. In this case you would want to locate a replacement frame and media between the furnace blower output and before (or in) the plenum chamber.

The plenum is the large sheet metal box that carries the warmed air away from the furnace and into the smaller air handling ducts.

If all else fails, write down the make and model of furnace that you have and do some searching on the internet for where the filter should be located, or ask a local heating contractor about where the filter should be located for your furnace.

Good luck,

Answer 2

All homes heated with hot air have some type of filter. Now if there is none in the furnace, sometimes it's put elsewhere.
You have registers that put out hot air when the furnace runs. But, somewhere in the house, usually downstairs, there may be one extra large register like 20 x 20 inches. That is where the cold air returns, and behind it is where you'll find the filter. The grill comes out with screws or it may snap in place. If you don't have one of these extra large returns, the filter is in or next to the furnace. If you can't locate it, you may need call a professional. A clogged filter will raise your heating bills.

Answer 3

There should be a place either above or below the fan that a filter will fit into. Some units have the filters above the A coil, as to use a downdraft airflow, and eliminate the need to install a filter slot between the heater, and the duct work.

Answer 4

The filter could be behind a return grill or inside the furnace itself. If you really dont have one, call an HVAC company and have one installed.

Answer 5

Talk to a local heating specialist to make sure but there is almost always a small thin slot for the filter to be installed in between the fan and the heat ducts. Any plumbing/heating technician would be able to put one in for you.

Answer 6

check where air is drawn to the combustion area if a filter is needed slots for one to slide in should be obvious. not all burners use filters

Answer 7

it should have one you may have to pop off a panel to see it it wont be in the open

Answer 8

yep