Do I Have to Drill a Hole Through the Wall for a Ductless Mini Split? - Ask the Expert Episode 268

Today's question is from Saliva.

"Hey Dan. Do your mini splits have to have holes drilled through the walls? I'm really interested in your products, but putting holes in the walls is not an option for me."

For ductless mini splits, you have to drill a hole through the wall. Though there may be other options. Strictly speaking, you could install a ductless mini split that ran a refrigerant line and the communicating wire through the window. There are some accessories on the market that have little window attachments.

That said, it is generally recommended to drill a three-inch hole through the wall. If you really want a mini split and you don't want to drill through the wall, well, it's possible. You just have to find a way to get the communicating wire and the line sets out to the condenser.

You first have to check with your local codes to make sure that whatever you're doing is okay. Also, a big line set going out the window isn't going to look great.

There are also some new alternatives to the traditional window units. We're about to get a U-shaped window unit from MrCool, which could look really nice and be very effective.

4 comments (view/add)
  • Vic Woodard
    Vic Woodard
    Posted on 7/26/2021

    Hey Dan, I purchased a Mr Cool DIY multi mini split with four heads. One of the heads is going on an interior wall that we cut open and will build out about an inch to
    accommodate the refrigerant lines which will run 40 ft underneath the house to the condenser. For added protection inside the walls we cut pvc pipe long ways and installed it on the inside of the cavity to act as a track for the lines.
    Question: do the refrigerant lines running underneath have to be wrapped with the tape since they are underneath the house and already in an insulated sleeve? Can we just wrap the portion in the walls an the portion coming out to the condenser.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/27/2021

    Wrapping them with tape makes them easier to handle, in my opinion, but it sounds like you would be fine in your installation without using the tape.

  • Chuck Dart
    Chuck Dart
    Posted on 7/21/2021

    I live in an early 1900's pier & beam house with concrete front porch and did not want an external 3.5" hole to the porch. Instead I built an interior "vertical fur down", ceiling to floor between windows, 34" wide and 7.5" (exterior dim) deep.  The air handler was pre-mounted on sheetrock with wood support, line set bent downwards, then attached to the fur down frame.  The line set went through the wood floor to the crawl space, out the underpinning on the adjoining wall to the condenser.

    I live in a rural area that does not have HVAC code. Not sure if this solution would have been passed code if we had one.

  • Paul M
    Paul M
    Posted on 7/20/2021

    I stumbled upon a great way to seal up the hole for my MrCool mini-split: Take that same 3.5" drill bit that you made the hole with and drill a few pieces of the spongy blue material that kept your unit safe in shipping. Out of these pucks of cushioning material, cut just big enough holes to fit your condensate, refrigerant & power lines (making sure the condensate line will drain). Stuff these pucks into the hole, then seal the outside with the clay provided.


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