Minisplit mounting question


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Old 06-02-15, 12:23 PM
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Minisplit mounting question

I am installing a minisplit. The directions are here:
http://ecomfort.com/PDF_files/Mitsub...e18install.pdf

But, I have a couple of questions for anyone that has some experience with these.

In the section titled "2-1. ATTACHING THE INSTALLATION PLATE"

1) It shows the screw holes to be used on the left and right side of the installation plate. In the bullet points to the left, it says that these holes should be on a stud--makes sense.

But, the screw holes on the right are directly above the hole that is to be drilled for the lineset.

Doesnt this seem a bit strange? This would mean that the only way to follow the instructions is to open the wall and re-frame, or to drill away the stud.

In order to put my 3 inch hole just to the right of a stud, I had to put the plate in a spot where the other specified holes dont hit a stud. I planned on using some of the many other holes or drilling my own. But the directions say that, to avoid vibrations, the ones shown in the image must be used.

2) In the bullets, it mentions a knockout. What knockout? Is it the oval in the middle? Any idea what that is for?
 
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Old 06-02-15, 01:08 PM
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If you can't get the holes to line up on a stud, just use some good quality drywall anchors to attach it. The indoor unit is not heavy at all, its nothing that good anchors cant support.

There might be a knockout on the sides of the unit if you are piping it along the interior wall. That's probably what they are talking about.
 
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Old 06-02-15, 01:48 PM
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"If you can't get the holes to line up on a stud, just use some good quality drywall anchors to attach it."

Really? I'm surprised.

I think if I went that way, I would do the drywall anchors in order to use the holes they specified, but would also drill a few of my own if needed, in order to hit some studs.

Is that what you meant?
 
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Old 06-02-15, 05:06 PM
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Exactly .
 
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Old 06-02-15, 06:00 PM
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Where I placed the orange lines should line up with the studs. The three blue circles are where the screws should be as the main unit hangs on those three cleats.

Your hole for the lineset should be just to the right of the stud.

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Old 06-03-15, 06:57 AM
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oh, I see. I misread the picture somewhat (thinking that some of the screws lined up when the didnt. For example, the two left/bottom screws are not under the one top/left screw. And the two right/bottom are not under the one top/right.)

But the instructions are also a bit unclear. They say "the fixing screws" should be on studs. Not the top fixing screws. That, combined with my thinking they all lined up, made me think that no screws could hit a stud.

Anyway...
I have already drilled my hole just LEFT of my stud (as opposed to the correct location which is just right of a stud.)

I suppose my only option is to open the wall and sister the existing studs with another piece of 2x4 to the left of each one. And then hang the plate from sistered pieces.

Or, would you handle it another way.
 
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Old 06-03-15, 10:14 AM
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Actually, if I'm going to open the wall at all, instead of sistering the studs with 2x4, would it make more sense (and be easier) to:
- trace the installation plate, then remove it
- then, cut the sheetrock out in a rectangle within the area of the outline
- replace the sheetrock with a piece of 1/2 plwood

Then, I wouldnt need to worry about screw locations at all. And, I assume it would all be hidden anyway by the unit.
 
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Old 06-03-15, 05:29 PM
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You only have about a 1/4" to play with between your bracket and the edge of the unit, so your hole would need to be precise. Using plywood would work, but you are comprimising your air/vapour barrier.

As mentioned above, just get some good drywall achors (screw in type or toggel bolts) and mountit anywhere you want. The screw in type achors are rated for 100-200lbs each, so there will be no issue with the unit not staying on the wall.
 
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Old 06-03-15, 05:33 PM
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"but you are comprimising your air/vapour barrier"
Do you mean because the plywood and sheetrock would have a gap (unlike two pieces of sheetrock that would be spackled?

As for the toggles, it just seems like it wouldn't, couldn't possibly, be strong enough. But I guess that is just coming from inexperience.

Sheetrock crumbles easy enough, it just seems that the weight of the unit would wear on it so that the screw-ins weaken. No?

Does that mean the one screw, in sheetrock with a toggle would successfully hold a 200 lb weight hanging from it? I find it hard to believe.
 
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Old 06-03-15, 05:37 PM
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I have mine (18,000 btu) mounted with screw-in drywall anchors, and it hasn't moved at all. The indoor units typically weigh only 20-30 lbs, so there is really not much weight to hold up. You should be able to get at least two screws into a stud no matter where you put the bracket, so use that opertunity.

under your drywall you should have some sort of vapor barrier, depending on how old your house is. You need to some how seal that back up after you cut it, that goes for the hole you drilled through the wall for the pipes as well. cualking the plywood edges as you place in back in is acceptable.

You might find this interesting. http://www.todayshomeowner.com/testi...cture-hangers/
 
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Old 06-03-15, 05:43 PM
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I planned to use "Great Stuff" foam (very carefully) to fill in the hole where the lineset and wires came through.

It is a new room, an extension built about 10 years ago.

I guess I will just use toggles in the spots where they say the screws must go (to stop vibration) and then hit a few studs (probably just two) in other spots.
 
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Old 06-04-15, 11:08 AM
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I never finished my vapor barrier comment.

The room is fairly new--about ten years old--but there is nothing special for vapor barrier.

It is just 2x4 studs. On the outside is plywood sheathing. On the inside is sheetrock. And between the studs are batts of insulation.
 
 

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