I seem to be stock piling used furnace filters, are there any uses for these things once the furnace is done with them? It seems a shame to throw them out; given that I change them once a month, there must be some way to prevent all this waste.

Air filter

This might be a bit off-topic but the filters could be used in some DIY project, which would make it on topic. So slightly off-topic question, looking for on-topic answers.


Seems to be a lot of talk about changing the filter so often, here is an exert from ehow.com

Industry Guidelines The industry standard for any filter is to change once a month for the highest level of maintenance. Of course, this may or may not be necessary for all homes depending on their specific environment and how often homeowners use their furnace.

  • just curious, why do you change filters so often? – shirlock homes Jan 7 '11 at 15:24
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    @Tester101 you change them once a month? I only change mine twice a year. I'm curious as to what the recommendation is. Have you ever considered an electronic air filter? My parents had one and it was great !!! the upfront cost was several hundred dollars but the filters were washable in the sink and reusable. – user45 Jan 7 '11 at 15:24
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    My furnace's air return is in the floor, and this part of the world is dusty. So the filter fills up pretty fast. I buy 3-month-rated filters, vacuum them after 1 month, and then replace them after another month (so sooner than their rated life) to try to keep the furnace happy. – Jay Bazuzi Jan 8 '11 at 4:28
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    If you want to get technical about it, when you replace the filter is completely dependant on how quickly it gets clogged. To truly test if it's time to change the filter you have to check the air pressure on each side of the filter when the blower is running. If there's a large differential, then it's time to change the filter. We run our blower 24/7 as a crude air cleaner, but only need to change our filter every other month or so. Doing it monthly surely lessens the load in the blower, but until you verify that your particular situation requires it, it may be overkill. – Adam Davis Jan 12 '11 at 1:12
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    in florida, i have to change my filter every 4 weeks or sooner in the summer. any longer and i can pull the dust off my filter like a lint screen in a clothes dryer. in the winter, almost never, even with my forced air heat. – longneck Mar 7 '11 at 3:42

While I cant think of any DIY project, you may wish to call or research as to whether that particular filter vendor provides recycling. If you have any friends or family with a fireplace or wood stove I bet they burn well. Barring both of those, all I can suggest is to buy washable filters in the future. You will pay a higher premium up front but it should pay off in the log run (and help you keep some junk out of the dump).

EDIT: Before burning, you should check that the filter is free of metal frames or added chemicals that could be harmful. If those are not present, the filter could also be shredded and composted (maybe).

  • my only concern with burning them would be the pollutants and metal wiring inside some filters, good idea though ! – user45 Jan 7 '11 at 15:26
  • @Scott Vercuski, very good point. I was estimating a vanilla paper fiber filter in a cardboard shell but there could be other stuff. Then again, if there are no other chemicals in it, I suppose it could be shredded and composted. I will augment my answer. – Bob Roberts Jan 7 '11 at 15:42
  • composted !! that's an idea if it's just paper and dust. – user45 Jan 7 '11 at 16:21
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    nice pun: "pay off in the log run" – Peter Turner Jan 7 '11 at 18:48
  • @Peter Turner, I assure, any humor is incidental and caused by negligence at best. – Bob Roberts Jan 7 '11 at 18:57

This does not help you with your stockpile of used filters that you have right now, but for the future you could try switching to a biodegradable furnace filter (there's a few when you search Google) or you could try using a reusable furnace filter so that you do not produce as much waste.

Keep in mind if you switch to a reusable filter then you need to maintain it monthly by washing it, therefore using more water and producing more work for your local water treatment plant or septic system while taking more of your own energy each month.


If you use 20x20 furnace filters, they work fine in front of 20" box fans (available cheaply) as room and work-area filters. Smaller, larger, and more rectangular filters can also be used, but they don't match the fan quite as well. No need for a frame - the fan's suction will hold the filter to the fan well enough when placed on the floor or another stable object.

Beyond that:

given that I change them once a month, there must be some way to prevent all this waste.

You are perfectly within your rights to change your furnace filter as often as you prefer. However, if they are not coming out obviously soiled, then you are wasting them, and the best way to prevent such waste is to use them in your furnace for more than the 5-10% of their lifetime that you are currently using them for.

I understand that the recommendation is to replace monthly, but you'll have to determine whether using them more fully is more important than providing your furnace with the least air resistance possible. It's a balancing act. But no professionals will recommend a longer period changing time due to liability. In some cases dirty filters cause significant problems, and the best way in the industry to avoid becoming liable is by insisting that customers follow an overly aggressive maintenance schedule.

It's not bad to replace it monthly, but as you seem to be discovering, it is wasteful unless you've already determined that you actually do have that much air contamination.

  • Good points. I probably don't have to change the filters so often, but given the money I just spent fixing the furnace (Which broke because the previous owner NEVER changed the filter) I would rather be more aggressive. Especially seeing as the furnace is old, and could use a break after the hell the previous owners put it through. – Tester101 Jan 12 '11 at 15:51
  • @Tester101 - I understand the feeling. Good maintenance prevents problems. I replaced my own blower motor on mine a few years ago as the prior owners didn't oil the old one, and it was not a sealed unit... – Adam Davis Jan 12 '11 at 16:22

I just made a replacement filter for my shop-vac using a 20X20X1 standard furnace filter.

First I cut off the cardboard edge & separated the cloth part from the chicken wire. Then I cut the cloth in a circle using the old filter cloth as a guide. I tested the strength when wet as we're talking about a wet-dry vac. The new filter I made seems more durable than the original (however it's not 10 years old either) not that I would need one of these each month much less 2 (my house uses 2 filters) but hey it's something. The whole project took maybe 10 min.

Additionally, I'm sure you could find a use for that chicken wire; maybe keeping rabbits out of the garden, or for a large stucco patch on the house. The cardboard would be recyclable of course.


Let's think about this one Tester. What can we do with a dust, pollen, allergen, mite, dander, pet hair contaminated paper product?????? Recycle it with other paper waste??? Not trying to be mean, actually just a bit tongue in cheek. Maybe a sawdust filter for a shop vac exhaust system???

  • Why the down vote? The shop vac filter seems like it might work. I was thinking maybe use them to strain paint, or as a coffee filter (Nothing beats a dusty cup of coffee). – Tester101 Jan 7 '11 at 16:07
  • I didn't down vote your question. Was just having a little fun with my answer, since I really didn't have a good one for you. I only ever down vote an answer if I know for sure it is wrong or can cause a problem or safety hazard if followed. I love to give up votes, it encourages more folks to participate. – shirlock homes Jan 7 '11 at 18:31
  • Please. I'm never gonna drink coffee at your place. LOL – shirlock homes Jan 7 '11 at 18:32
  • I noticed your answer had a down vote, I was just wondering why it was down voted. – Tester101 Jan 10 '11 at 13:17

Back to the question...what to do with the use air filters. I too seem to collect them and each spring when the cars are pulled out of the garage long enough for me to put the sleds away for another year, I lay them on top of drywall in between the rafters in the attic. I have even gone to the extent of stapling them to the ajoining bedroom wall which may or may not have insulation in that very same attic. That room gets cold in the winter and hot in the summer so instead of throw them out I try to save a little on my energy bill. Does it help? I think so. If not, at least I don't have to look at them in the basement! :-)


I'm Jean Nichols from Furnace Filters Canada.

Let me suggest 2 solutions if you want to reduces waste.

Replace your pleated filter by a permanent washable filter. Noveko is selling most standard furnace filter size. When they are dirty, just was them and use it over and over...

Last option, Go for LEED! Try to find the Camfil 30/30. The Camfil Farr 30/30 may be used to meet requirements of the U.S. Green Building Council (“LEED®”) in terms of efficiency, energy savings and reduced disposal impact.

Good luck.

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