Recently moved into a new home and am trying to get new furnace filters. The house has this unit: https://www.ecomfort.com/Goodman-ARUF49C14/p58566.html , which looks like its called an Air Handler.

I found the filter cover at the bottom of the unit but there doesn't appear to be a filter currently in it and the area is blocked by some piping.

Photos attached to explain better: https://ibb.co/album/xJbMjL

My two questions are:

  1. It looks like the angle is pretty tough to get a filter in there, can I somewhat bend the filter to get it in? Any other ideas on how to get it in?

  2. What filter size does the unit take? I don't see anything on the unit itself and when I read the manuals, I see different info.

This manual says

"When using the factory filter rails, a nominal 16x20x1”, 20x20x1” or 24x20x1” (actual dimension must be less than 23-½”x20”) filter can be installed on a B, C and D cabinet respectively (the cabinet size is the seventh letter of the model number)."

However, the first link I posted lists the filter size as 19" x 20".

Appreciate any guidance.

  • Where in the first link is the 19" x 20" specification? I don't see it. Commented Nov 15, 2021 at 18:39
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    You may be able to use a quick disconnect fitting on the pipe. Allows you to temporarily disconnect the pipe for changing the filter. I didn't post this as an answer because I can't see the rest of the pipe to know if it would work and jay613's answer is better. Commented Nov 15, 2021 at 19:44
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    According to your post, you have a Goodman furnace, model ARUF48C14. According to your quote from the manual you use the 7th character of the model number to identify the filter. By my counting, the 7th character is a C, so you'd use a 20x20x1" filter. Of course, you'll probably need to follow the instructions in jay613's answer to actually get the filter in place.
    – FreeMan
    Commented Nov 15, 2021 at 19:49
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    The Goodman instructions you cite in your comment above, at pg 11, Section 10, for the ARUF49C14 furnace state the furnace uses a 20x20x filter, just as @FreeMan notes. I would take the manufacturer's instructions as more accurate than a mere statement from the vendor. Commented Nov 15, 2021 at 21:55
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    Per @PlatinumGoose - Yes you could add the quick disconnect fitting (union)right where the PVC exit the furnace. Then it would be easy to slide the filter in and out by just removing the vent pipe as you stated. Commented Nov 15, 2021 at 22:37

2 Answers 2


If you want to install the filter in the air handler using its filter rails you need to reroute the condensate drain. It's in the way, you can't use those rails now. I would put a 90 degree bend to the left just as it exits the housing, so it drops down to the left of the unit. And move the vent so it's to the right of the unit. Or remove the vent, it's usually not necessary and sometimes does more harm than good.

enter image description here

OR you could move the filter to the intake register. If it's big enough, replace the grill, the one you can see in the second picture, with a filter frame and then you replace the filter from the room on the other side. Of if the grill is too small for the requisite filter you can replace it with one that hinges open, and install a filter frame in the wood plenum beneath the air handler. So you still access the filter through the grill in the other room.

As to what size filter you need if you use those rails ... you could just measure it. But the exact model number and the manual will answer that question.

Edit: I'm adding this to the answer after it was already marked correct but I think the correct answer is in the comments so I'm adding it here. The elbow and the vent pipe currently installed on the air handler turn out to be push-fit, not glued. They don't leak because they are a good fit and there is never any pressure in this pipe. So to change the filter you simply pop the pipes off their connections. Maybe wouldn't hurt to replace them with compression fittings but it ain't broke. If you do it carefully you'll retain the water in the trap but otherwise just pour half a cup of water into the trap before pushing it back onto the handler.

  • Thanks. Any guesses why the piping would have been installed that way? It seems like it wouldnt be the best place given that it blocks the filter slot. I'd prefer not to re-route it as I would have to hire to someone to do it. Also, the grill in the second picture has a post that runs in the middle of it so it may be tricky to get around it. Is the vent the vertical pipe in the center of your photo? I just discovered that piece slides off easily so if I remove it, I may have a bit more room to try and squeeze the filter in but I would still have to bend it a bit. Thanks again
    – Guest89
    Commented Nov 15, 2021 at 21:22
  • Hanlon's Razor suggests that the installer was lazy and not paying attention. Commented Nov 15, 2021 at 21:47
  • Yes that vertical pipe is the vent. If it is loose fitted and slides out easily, maybe some part of the condensate trap (the P-shaped pipe or the elbow above it) is also fitted loose, and you can thus easily gain access to change the filter. Just refill the P trap with water after. If not, as someone else suggested, maybe you could replace one glue joint with a compression fitting. If I can validate that idea I'll add it to the answer.
    – jay613
    Commented Nov 15, 2021 at 22:24
  • As to why it's installed that way, the more interesting question is why the condensate drain and filter door are designed the way they are so that the most obvious way of installing the trap causes problems? Can't answer that.
    – jay613
    Commented Nov 15, 2021 at 22:26
  • Thank you, the elbow above the trap came out very easily (not sure if thats a good thing) but I was able to slide a filter in. A few drops of water spilled out, but that trap should always have some water in it? I'll put a bit back in if so.
    – Guest89
    Commented Nov 16, 2021 at 4:38

If the attached "Users Manual" matches your unit, then the filter is located at the bottom of the unit as shown below:

enter image description here

According to the Users' Manual:

10 Return Air Filters

Each installation must include a return air filter. This filtering may be performed at the air handler using the factory filter rails or externally such as a return air filter grille. When using the factory filter rails, a nominal 16x20x1”, 20x20x1” or 24x20x1” (actual dimension must be less than 23-½”x20”) filter can be installed on a B, C and D cabinet respectively (the cabinet size is the seventh letter of the model number).

Users Manual

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