Mitsubishi MXZ-SM48NAMHZ2 Condenser Wall-Mount

eheinkel · October 8

Hi experts! This Mitsu ODU is wall-mounted using QSWBSS. https://www.coldaircentral.com/products/mitsubishi-electric-wall-mounting-bracket-qswbbss?srsltid=AfmBOopdDIHJ7xUtQDH4cOg_04tFgfxYhEe-dsPdlyrTRhH7dwHO7kGj

It weighs about 265 lbs. and the bracket is designed to hold 500 lbs. I am concerned about stability - basically if you touch it at all it sways a bit. Any recommendations? I could form and pour a slab with threaded rods etc, but i wanted to keep the unit a foot or two off the ground due to potential snow in Northern Wisconsin,

Thank You-

E

John Abbott · October 8

I install mini splits and wall mount is my method of choice for mounting heat pumps Because of the leverage of the tall ODU some deflection is inevitable however there is in my opinion no cause for concern I have installed over 50 of the units in this manner because of extreme weather and snow depths here in NH. Heat pumps periodically run through a defrost cycle so they must be a minimum of 6 inches above grade or pad to prevent ice build-up under the compressor and possibly damaging it. Hope this helps, I am a trade professional.

John

Ironman · October 8

If the unit is bolted to the brackets in four places, there should be little or no deflection.

This assumes that the brackets are properly anchored to the wall.

pecmsg · October 8

I certainly hope it’s bolted to that bracket. It’s normal to have a little bit of movement with that set up.

Kaos · October 9

Is that bracket on masonry or wood construction. These minisplits are pretty quiet but they still produce a fair bit of low frequency vibration. You don't want your outdoor unit mounted onto light framing as it can carry the vibrations through the entire house (been there, had to move it).

The unit should be either ground mounted or onto the foundation. You can get the other style L brackets that go down which might let you mount onto the foundation.

Also watch how the refrigerant lines enter the walls. You want two bends in the lines between the outdoor unit and the wall to reduce noise transfer, they should not be straight back.

As for the wobbly bit, they all do it. You can install check strap near the top as a piece of mind.

clammy · October 10

Personally i stopped mounting mini splits to wood framed construction or mounting them directly on blocks at ground level being they end up full of mulch . i usually buy the base stand and set it on leveled concrete lentils makes for a better job and zero chance of noise or vibration being transmitted to the building . It also give you some room for cleaning the outdoor coil .

peace and good luck clammy

steveray · October 10

In the past we have installed a 3/8" galvanized threaded rod to the top right rear of the unit, either by drilling a small hole in the jacket and nutting it on each side with washers or with a galvanized wall plate screwed to the Jacket. We attach it to the wall with a galvanized 3/8" wall bracket. This was mostly to satisfy customers who inevitably go up to it and start pushing on it and saying" is this safe like this?"We have installed alot of these and had no problem with the brackets, other than them rotting out prematurely so we switched to the Stainless Steel version on all installs

Voyager · October 10

Was the siding removed before the bracket was installed? It it was installed simply by squashing the vinyl siding, then I would expect some movement.

Jack · October 10

I installed a two ton on my place in ‘08 with a wall mount. I was so paranoid I thru bolted it. It was wooden I” interior so I was able to dress it up. I wouldn’t have made a cent on that job. When your paranoia gets to you maybe it is time to put a stiff-leg to the ground.

ronaldsauve · October 10

I am a trade pro in Maine myself, and I prefer the wall mounts, although sometimes I’ll use stands on a slab if required. But for the wall mounts I don’t use the included screws for fastening to the wall. I use short heavy duty structural screws. Because I can’t always count on landing them on studs, I use a structural screw in every single hole in the wall bracket. I like redundancy. Safe than sorry is my mantra.

GW · October 10

If it works, it works! If you want 'solid' get it off of the wall bracket and onto a ground mount.

I personally don't mount those big boys on the framing-siding. But I've seen it done in my travels.

If you can hop on on the end of those 'arms' and it holds you and the unit, you're good to go. (unless you're a bigger person, don't bother). I'm 180 or so, I would have hopped up there.

eheinkel · October 11

Hi all! Thank you for all of the feedback. To answer a few questions… This is the stainless steel version of the mount. It is bolted through the siding and OSB and into 2x6s I mounted as backing using the 4” lag screws provided. The top of the mount is very solid, but as Voyager mentioned, some squishyness results from how the bottom of each L rest against the vinyl. While lifting the unit onto the mount, I noticed that the right side of the unit weighs considerably more than the left, resulting in a slight list to the right, even after trying to adjust. This bothers me as well. Kaos, could you expand on your recommendation of two bends in the copper line sets? I have the unit mounted so the line sets will have one 90 degree bend and then enter the house in the center of a 2x6 interior wall between the garage and the house to keep the lines hidden. I cannot seem to find a nice heavy duty stainless or aluminum ground mount anywhere, just cheap painted steel etc. I am leaning towards having a custom aluminum mount built from 3” L at about 20” tall and pour a 6” concrete slab with embedded threaded rods.

Voyager · October 11

That mount is likely fine if installed correctly. Mounting it over vinyl siding isn’t correct. The siding should have been cut away, most easily in a square section and replaced with 3/4” PT plywood screwed to the sheathing and then trimmed with vinyl J-channel and caulked well. Then attach the bracket to the plywood using lag screws long enough to go through the plywood into the studs. I bet you would have very little movement in the unit if mounted that way.

Kaos · October 11

https://forum.heatinghelp.com/discussion/comment/1813788#Comment_1813788

Normally the fittings on the unit point towards the back. From there you want one 90 to go up/down/left/right and short length of straight run than another 90 to go through the wall. This gives this connection some compliance so any vibrations won't be transmitted into the stud wall. Some sloppy installers coil up the left over lineset behind the unit which is also very effective but ugly.

You will not regret ground mounting the unit. Only way I would mount otherwise is to the foundation but that might be too low for you.

If you can't find a taller ground mount, you can make one out of unistrut. A couple lengths plus some fittings and you can make it fit exactly your unit.

Another option is to pour a couple of sonotube posts instead of a pad and put a section of Unistrut on the top to pick up the feet on the unit.

The SM48NAMHZ2 is pretty big unit. I hope you are not looking to connect a half a dozen or more individual wallmounts to it, one for each bed. This tends to not work well and crease comfort and efficiency issues as the smallest wallmount is about 3x oversized for a typical bed. A couple of larger wall mounts in the living space and and a ducted unit for bedrooms does work reasonably well.

Mith · October 13

It shouldn't be mounted to the siding. As noted the siding should be cut away under the bracket and a flat mounting surface created with pressure treated plywood.

The unit needs to have at least a little freedom of movement or it will transmit much more vibration to the structure than if it is properly mounted. If you used the vibration damping hardware that comes with the unit (or is it the backet? Can't remember) to attach it to the bracket there will always be a tiny little bit of play, and over the height of the 2-fan Mitsubishi units, it will allow a noticeable amount of horizontal deflection.

I agree the smallest available indoor units for the Mitsubishi multi-splits are about 2,000 BTU too large. My solution is to add an MHK1 or MHK2 to units in smaller rooms and cut the two jumpers on the indoor unit's control board that stop the fan when the zone is satisfied. It is operating the fan on extra-low to circulate air over the coil for temperature measurement that cause the overheating/overcooling to get really bad - with a wall stat and those jumpers cut the problem is basically eliminated without the need to run ductwork.

Mitsubishi MXZ-SM48NAMHZ2 Condenser Wall-Mount

Comments

Categories