We bought the house recently. Heating system was recently installed by the previous home owner. I cannot believe they did not think of this but the place for filter is inside the furnace. The problem is that there is a pvc pipe in the way. PVC is for condensation. I have to bend the filter from under the pvc pipe and then try and slide it. Also it does not slide easy at all. there are still some open areas which I can above the filter. Sometimes filter tears. It is such a pain every 3 months!! I did find that outside the furnace there is a flex duct its some sort of heavy fabric which is tapped to the duct system. I assume they use this in case duct system doesn't line up. Is there anyway I could have a filter location installed there? Or cut the duct system and install it somewhere in between?

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  • 1
    Have you tried removing the horizontal PVC condensate pipe? It’s hard to tell from the picture, but the joints don’t look glued.
    – Mark
    Commented Apr 29, 2018 at 11:48
  • Can you access the filter from the other side of the furnace? Commented May 13, 2019 at 12:05
  • @Mark there are cables zip tied to it, so it's unlikely to move much
    – simpleuser
    Commented Aug 25, 2019 at 3:51
  • The filter is normally outside the furnace cabinet, in the short horizontal section of the return trunk. Is there some sort of equipment behind the patch in the bottom of that trunk that would prevent you from reconfiguring to make that so?
    – isherwood
    Commented Sep 10, 2020 at 17:10
  • Oh. Really old question. Sam, you still around?
    – isherwood
    Commented Sep 10, 2020 at 17:13

1 Answer 1


Actually, the filter seems to be installed in the wrong location. It’s installed on the wrong side of the “air filter tray”.

If you look closely at the bottom of the filter, the metal plate just to the left of the filter, has a “J-shape” at the bottom. That “J-shape” is made to hold the filter vertically in position, so it doesn’t slip down and not cover the intake opening properly and is called the “air filter tray”.

Also, it appears there is a sufficient space (vertically) for the filter to fit on the left side of the tray too. (NOTE: Before you move the filter to the left, I’d check with your manual, if you have one, and if not, I’d check with a HVAC contractor...because there are wires in that space too. Very unusual. Maybe the wires can be moved out of the way so the filter fits snug against the intake.)

The reason it’s important to install the filter in the proper location is because it needs to “fit” properly and completely cover the air intake. The reason THAT is important is because you don’t want air seeping around the filter and carrying dust, etc. into your furnace. The reason THAT is important is because dust will build up on your heating coils and could ignite when the coils are turned on. (Even if it doesn’t ignite, it will make the furnace very inefficient because it “insulates” the coil do it doesn’t give off all the heat.)

I’d try to cut the condensate pipe so you could temporarily remove it, which would then allow you to remove the filter. Then, when new filter is installed, you could reinstall the pipe...

  • 2
    'just to the left of the filter, has a “J-shape” at the bottom' - that just looks like a short tab to me, possibly to hold the vertical metal piece in place. It does not look like it is much wider than an inch or so. Given the danger of the charger starter capacitor in there I'm not sure I believe a filter belongs in that part of the case at all.
    – simpleuser
    Commented Aug 25, 2019 at 3:58

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