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Cut-to-fit filter in a minisplit head?

DCcontrarian | Posted in General Questions on

The recent conversation about gunk building up in minisplit heads had me thinking if there was any technical reason they couldn’t be fitted with better filters. I mean, HVAC systems are fitted with filters for a reason, the manufacturers of minisplits seem to have exempted themselves from that requirement.

The obvious problem is finding  filter that fits, but there are various places you can buy cut-to-fit filters, marketed to people who have oddball sizes that aren’t supported. Any reason not to try one of those to replace the “panty hose” filter most heads come with?

Thanks.

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Replies

  1. Malcolm_Taylor | | #1

    Dc,

    After reading that discussion I'm still unclear: Is the gunk that can't be removed by vacuuming entirely due to using them for cooling, or is it always a problem, even when just used for heat?

  2. Expert Member
    DCcontrarian | | #2

    Cooling definitely makes it worse, because the coil is wet and the gunk hardens.

    It's also more convenient to pull out a filter and throw it away than to vacuum something up high.

    1. Expert Member
      DCcontrarian | | #3

      Also, you want to be filtering that gunk out of the air that you breathe anyway.

  3. freyr_design | | #4

    I wonder if you could integrate it with a wood surround that also covers the head to make it look nicer. You might need ir repeater.

    Or even a drywall surround

    1. Expert Member
      DCcontrarian | | #5

      I'd want something you could take off if you needed service.

      I was thinking tinted acrylic over the IR receiver, that's commonly done with home entertainment cabinets. But yeah, then you could just put a filter holding grille on the intake.

      1. freyr_design | | #6

        Yes I was thinking something built like an upper that could be attached on top with like two screws, or even a hook mechanism. I think a filter grill on top might look a bit funny, but maybe not.

  4. Expert Member
    Akos | | #7

    This is my filtering add on. Regular furnace filter cut in half and a good dose of gaffer tape. The blowers on wallmounts are very weak, this filter cuts the flow by a bit more than 1/2. In my case, it is something I wanted since the unit is oversized and is in my bedroom.

    For any real filtering that won't effect performacne, you'll need pretty large surface area. This is in the ballpark:

    https://www.greenbuildingadvisor.com/article/this-minisplit-wont-dehumidify

    1. Expert Member
      PETER Engle | | #8

      Yeah, that would be my biggest worry. The fans on these things are super quiet, but also very weak. Any filter that does much of anything will probably do some serious damage to air circulation. In your case, a single head in a bedroom doesn't need much throw. But a wall mount in the great room might not work much at all. Of course, the rest of the cover has to allow as much of the fan forced air as possible, too.

      FWIW, now that VT is embracing minisplits in a big way, I see lots of companies popping up that claim to be able to clean them. I'm still holding my breath on that one.

    2. freyr_design | | #13

      That linked filter head is pretty funny… at what point do you just get a concealed duct mini split?

  5. walta100 | | #9

    Has anyone tried one of the kits for cleaning mini splits?

    They seem to be very popular in Asia where it seems everyone has a mini.

    The verbiage in the photo is not helping sell the product.

    Walta

    1. Expert Member
      DCcontrarian | | #10

      On the other hand, if there's sewage in there I want it cleaned ASAP, so I'm buying the kit.

    2. tobym | | #12

      Yes, I did. I got one of those kits from Amazon. Works very well in preventing spills against the wall. Would also recommend to hook-up a shop vac on the mini split drain as well.

  6. sergkingroad | | #11

    Some manufacturers will include a clause on their instructions that states it is okay to cut the filter, while others do not.

    1. Expert Member
      DCcontrarian | | #14

      There are filters that are sold as "cut to fit" for people with oddball equipment.

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