Minisplit Rear Mount question

[nconn]

I have a minisplit from EG4 that I will mount to the rear of my bus above the door. My question is how did you all secure the outdoor unit on the inside?

I see many videos of people installing these above the door but nobody shows the inside bracket. Surly they are not bolting a 100lb object just into the sheet metal... Well I sure hope they are not.

I plan on using L brackets made for under body storage boxes. I just need to figure out the inside bracket.

[fo4imtippin]

If you have some angle iron or flat bar on the inside, its not going anywhere. two pieces of 2in wide 1/8 steel flat bars. Drill holes in them and put bolts on the backside of the angle bracket. I have vertical channels about 30 in apart on my bulkhead, so if i were to mount it, i would weld the flat bar to those just to hold them in place for ease of install.

[Rucker]

I used standard home depot white shelf brackets-the sturdy kind. They are securely screwed into the inner shell of my fiberglass bus wall with predrilled holes.

Think about how much force a single screw can withstand, then determine how many screws you'll need to resist the forces of the unit. Do a little googling to see what the screws can support. If you are nervous, add a safety factor by multiply the number of screws by, I dunno, 2x, 3x? Whatever your comfort level is.

I don't think vibration will be a factor; but I do consider any weight cantilevered off some bracket to be worth monitoring periodically.

[Jolly Roger bus 223]

Originally Posted by Rucker

I used standard home depot white shelf brackets-the sturdy kind. They are securely screwed into the inner shell of my fiberglass bus wall with predrilled holes.

Think about how much force a single screw can withstand, then determine how many screws you'll need to resist the forces of the unit. Do a little googling to see what the screws can support. If you are nervous, add a safety factor by multiply the number of screws by, I dunno, 2x, 3x? Whatever your comfort level is.

I don't think vibration will be a factor; but I do consider any weight cantilevered off some bracket to be worth monitoring periodically.

rucker
do you mind sharing a picture of how you mounted yours?
my short bus project where i want to hang my outdoor unit is fibre glass and i have gone crazy trying to figure out a steel support system in the back wall in to the inner metal wall to support it because i dont trust the fibre glass mainly cause i have never worked with it.
the only other spot i have is on the bottom of the back door and use stainless braided flexible refrigerant lines to handle the swing of the door.

[Iceni John]

Is it too big to go under the floor? It will be inconspicuous there, yet still get plenty of air and be shaded. I put mine under the floor directly above the front axle, but that option won't work for FE buses.

John

[Jolly Roger bus 223]

yes
the short bus is a van cutaway.
3500 collins body

[Rucker]

Originally Posted by Jolly Roger bus 223

rucker
do you mind sharing a picture of how you mounted yours?
my short bus project where i want to hang my outdoor unit is fibre glass and i have gone crazy trying to figure out a steel support system in the back wall in to the inner metal wall to support it because i dont trust the fibre glass mainly cause i have never worked with it.
the only other spot i have is on the bottom of the back door and use stainless braided flexible refrigerant lines to handle the swing of the door.

Ha! I mis-read the OP's issue and provided a response not to mounting the outside unit (condensor) but rather the inside unit (evaporator). It's the mounting of the inside unit I described. Apologies for the confusion!

My condensor is not mounted on the chassis fiberglass shell out back-it's mounted on the bumper extension. I didn't see any easy way of securing it to the fiberglass shell.

Do you have pics of the area you are talking about? Maybe that will give us some ideas to share with you.

[Jolly Roger bus 223]

i do not but the body is sheet metal but the front and rear caps where the flashers are or fibreglass outside and metal inside.
with of course the 10-12" wiring chase.
i have pretty much decided on either the door or rooftop.
have a plan for the door but just heard a friend is redoing an rv and will sell me his two working roof top units with everything for 25$ each.
never wanted to cut a hole in the roof and take up room for solar but am on the fence again?

[Rucker]

I would pick up the rooftop units but frankly they are incredibly loud. Check also their power requirements because they may only run from a generator.

There are a few threads here that describe success installing the condenser unit under the bus. Depends on the bus, but that would be preferable to door mounting. I would be very skeptical that you could insulate the flex lines well enough to avoid lots of condensation.

If you opt for upper rear wall mounting I would recommend if you make a bracket for a shelf such that the vertical part of the bracket that secures the shelf to the rear wall of the bus be at least as long as the height of the condenser unit. Preferably longer, maybe incorporate propane tank holders on the bottom of it, or some other exterior storage. This is to minimize the tendency of the condenser to rock.

As mentioned my fiberglass chassis, that is, two layers of thick fiberglass separated by a 1" fiberglass-impregnated corrugated cardboard. My bus is a little over twenty years old and pretty much every compression mount had crushed that cardboard, whether it be the window flanges or through-bolts for the Q'straint handicapped hardware. Lots of cleaning out the cardboard and retrofitting plywood stacked to the thickness of the gap. The only exception was the Trans-Air evaporator unit mounted to the ceiling inside. In that case there were two relatively long aluminum channels secured to the roof which was used to mount the bolts holding the evaporator. My roof is fine because there was no real compression to the fiberglass system, just gravity.

Here's my setup: https://www.skoolie.net/forums/membe...cture28928.jpg

If your exterior fiberglass shell is relatively thick and hard you might be able to fabricate an external bracket that is through-bolted in enough locations to distribute the compression loads to the wall system. Also, any curve in the fiberglass will add significant rigidity, so if there's a way to partially curve the upper part of the bracket to match the curve or transition from the wall to the roof that will certainly help. Not sure if that's an option for you.

VHB tape does not hold up under shear forces so you can't rely on that alone but adding that behind the brackets will definitely not hurt.

[Gorzie]

I used some strong C channel and large washers inside. I made the outside brackets and the top inside cross support out of the same thing since the pulling force is out. The bottom I figure is pushing in so the large washers I felt were fine. I also used Grade 5 or 8 bolts.
I put in a wood frame for the inside unit to attach to.

[Rucker]

Thanks Gorzie! This is exactly what I imagined it would look like. There you go, Jolly Roger!

[nconn]

Hey everyone! Thanks for your recommendations. I got the brackets mounted in a way that I’m not worried about them. I welded a bracket on the inside to transfer the weight to a supporting structure. I could’ve used bolts but decided to try and weld it.

I posted a video quickly showing what I did.

https://youtu.be/TR8LY46KKkk

[joeblack5]

Mostly the outside condenser unit has to be below the inside unit.. also piping should be able to drain residual oil in the freon back to the compressor. Cadillackid probably can give you an expert opinion.

If you use the unit while driving and it is mounted behind the rear axle then you can have a lot of oil flying around inside your compressor because the amplification of the road unevenness.. remember the fun of sitting in the back.

My two cents.

Johan

[Jolly Roger bus 223]

if the indoor if the outdoor unit is above the indoor unit it is recommend and kind of needed to install an oil trap loop.

[nconn]

It will be at about the same level. I will look into a Oil trap loop. Thanks!

[ermracing]

I have basically the same setup for the condenser on the back of my bus. One suggestion, which I have yet to do is - put some flexy tubing to connect the copper lines to the condenser to eliminate vibration issues.

[Jolly Roger bus 223]

refrigeration supply sells stainless steel braided flex lines in 3 foot lengths with braze connections.
they run about 30$ each around here.

[cadillackid]

Originally Posted by Jolly Roger bus 223

if the indoor if the outdoor unit is above the indoor unit it is recommend and kind of needed to install an oil trap loop.

THIS.. I ran oil trap loops in my home units because the indoor units are in the basement and the outdoor units are above ground.. although my recent Fujistu unit (2022) said to absolutely NOT install oil trap loops unless the outdoor unit is 15 feet or more Above the indoor.. so read the install book for your unit and see what it says.. you may or may not need a loop.. that said *DONT* coil up extra lineset behind your unit as you can create traps that are unwanted.. doing it right means buying a good flaring tool and learning to cut flares.. I use coated copper flare seals on my units just because a lot of the brass fittings on chinese units are not perfect.. even cutting new flares on the copper pipes didnt always work..

[Dbacks2k4]

Originally Posted by cadillackid

that said *DONT* coil up extra lineset behind your unit as you can create traps that are unwanted.. doing it right means buying a good flaring tool and learning to cut flares.. I use coated copper flare seals on my units just because a lot of the brass fittings on chinese units are not perfect.. even cutting new flares on the copper pipes didnt always work..

A lot of those smaller units come "pre-charged" for a certain length - I assume if one were to shorten the line properly the amount of refridgerant would also need reduced?

Alternatively, if one didn't want to shorten the line set is there a "lesser of 2 evils" way to route extra lineset to avoid pitfalls like undesired loops?

[Rucker]

Some linesets do come precharged, or already filled with refrigerant. Stating the obvious, that's to make it easier to install (no need for a vacuum pump or skill).

The only way to shorten those lines is to remove the refrigerant (venting it is illegal, and who's gonna spend a hundred bucks on a proper recovery, so the whole idea of charged linesets is completely problematic in my mind), and then ironically you might need to add refrigerant because the lines are empty and there's only so much precharge in the unit itself.

Coiled lineset just seems dumb to me, but having said that there was a post elsewhere about some bus with a minisplit always losing refrigerant and I pointed out their condensor mounting on an extended bumper probably had quite a bit of movement whereas their lineset connection looked pretty direct and rigid, and they might consider a loop or other longish section perpendicular to the potential travel to prevent such problems. Same thought for your setup, perhaps that would figure in.