Mini-split two heads and Transformer

ArtGill · June 24, 2016, 06:49:09 PM

My project is to install a mini-split with two heads. My present design is to run the 220v ac units using a transformer that has 120 vac in. These unit are a ceiling cassette units that I will mount in the ceiling where the escape hatches were/are.

I have taken the first step and purchased a Daikin system with an 18,000 btu outside unit, a 9000 btu cassette for the bedroom and a 12,000 btu cassette for the front of my bus. I decided on the Daikin brand because: You can get parts to repair, it has county wide support and my technical support source and friend recommended Daikin. Daikin is widely available and sold in many areas by United Refrigeration (UR).

So far I have opened one cassette and I am studying the manual. I need to design a mount and a weatherproof box to fit over the cassettes.

I promise pictures in my future post.

Art

jcdillin · June 25, 2016, 06:24:32 AM

Very interested to see how these work out for you. I was planning on running the same way, except I want to run mine from a inverter on the house batteries.

Oonrahnjay · June 25, 2016, 09:17:17 AM

Yes, I have only heard good things about Daikin. My plan (since I have "two zones") has been to run two separate units on 120v but the thinking about the 240V dual head arrangment has had me thinking. To be able to run the two head units (although they'd be near each other) on a single compressor would sure save installation volume, plus I'd only have to deal with one set of ducting for fresh air into and hot air out of the condenser.
I'm up to my elbows in alligators with my engine change so I won't be ready to move for a few months but I'm very interested in your experience too, Art. I was down at the Cape Lookout 50th Anniversary event last weekend -- made me remember how nice "Down East" is and how I should visit more often; when you know more, maybe I could drop by and have a look at your installation.

bevans6 · June 25, 2016, 09:45:11 AM

In a big FWIW, I recently got inspected and asked where my mandatory escape hatch was. I said the stock bus escape hatch is fully functional as are the windows that aren't covered by walls. Which led me to ask myself if that was a serious question that I had better answer right, or a random question that was just off the cuff. Therefore I discovered that it appears that escape hatches are mandatory in RV's. Just a thought as you re-use your escape hatches for AC mounts. I think most RV have one big window that is an escape hatch, for sure I never saw a roof hatch on one (not that they don't exist, I'm sure).

thomasinnv · June 25, 2016, 10:24:00 AM

Brian the only factory built rv I have ever seen with a roof escape was a cabover truck camper. Just an oversized roof vent basically.

ArtGill · June 28, 2016, 06:20:40 PM

I have opened the cassette and it appears well built. I have come up with an mounting plate design to go on the roof with hole in the middle for the cassette to extend through and to support the cassette. This plate will be sealed to the roof and made water proof. I'm going to have a one inch square welded all the way around the outside edge of the plate. This will provide enough thickness that I can drill and tap for bolts to seal the cover to the plate. I expect the aluminum plate and bar to arrive tomorrow. Once I have the plates cut and welded I will look for someone to make aluminum covers. Pictures to come.

Seangie · July 02, 2016, 02:20:52 PM

Quote from: ArtGill on June 28, 2016, 06:20:40 PM
I have opened the cassette and it appears well built. I have come up with an mounting plate design to go on the roof with hole in the middle for the cassette to extend through and to support the cassette. This plate will be sealed to the roof and made water proof. I'm going to have a one inch square welded all the way around the outside edge of the plate. This will provide enough thickness that I can drill and tap for bolts to seal the cover to the plate. I expect the aluminum plate and bar to arrive tomorrow. Once I have the plates cut and welded I will look for someone to make aluminum covers. Pictures to come.

Make sure tou have enough wall on the evap condensation collection pan for the water. These things put out gallons of water. Best to have a drain on both sides of the pan and make sure your drain runs pretty straight downhill.

That was the most overlooked part of my installation when I did it. We would go around corners and Id get a good bit of water dripping on my head. I even remounted the inside unit at a steeper angle to help with the runoff and still would have water flowing out of the pan.

-Sean

brmax · July 02, 2016, 05:09:58 PM

Sean what do you think one needs a 2" deep or another idea if ya can, I had an interest in these awhile.

Floyd

ArtGill · July 03, 2016, 07:38:15 AM

The Daikin cassette has a condensate pump built in, but I will check the depth of the pan.
I waiting on the shop to cut and weld my base plate out of 1/4 Aluminum. What are some suggestions to mount this plate to my roof. It needs to leak proof for going down the road and hold the unit on. My roof appears to be stainless or aluminum with a little sagging between ribs and it is painted. On the coast we use 3M 5200 for everything, but is there something better that doesn't require screws? Has anyone heard of a two part epoxy call "metal Epoxy"?
Art

brmax · July 03, 2016, 12:52:48 PM

If this area inside is free from ceiling then the options are a few more, I think better just because drilling for bolts or rivets for the mounting.
On your base plate setup, with more of your description or pics I might consider it the permanent hd mount being riveted with a bead of 5200 on the outer edge, but have studs on the very top so mounting the condenser however can be mounted as you require.
Again not sure the picture in my head is the right show !, same channel though

good day
Floyd

ArtGill · July 03, 2016, 04:13:55 PM

The unit is designed to fit in a 2 x 2 grid type hanging ceiling. The unit is designed to be supported from the rafters that the ceiling is hung from. My present plan is to put adjustable feet where the supports from the rafter would go and nut on both sides of the bracket on the side of the unit. The 1 x 1 aluminum bar that will be welded around the edge of the plate is provide for drilling and taping holes for threaded studs. The purpose of these studs is to hold down the weatherproof cover over the unit.

So, my question is there some way to "glue" this plate to the roof without putting holes in the roof. My concern is about leaks that I will not find until after the interior is completed.

Thanks, Art

DoubleEagle · July 03, 2016, 07:20:41 PM

I am not visualizing what you are doing exactly, but when it comes to putting something on the roof I would not rely on just one method of adhesive. A combination of solid connectors and adhesive might be safer. The sun is going to bake your roof, and will whatever adhesive you use last indefinitely?

brmax · July 03, 2016, 07:29:04 PM

Ok I have a lot better idea of the project now, but I cannot at the moment name a product.
You and I both know so many car, truck and trailer type body's use some adhesives and have for many years.
I know we have mentioned a few names of stuff here but knowing well there are many companies that make this type stuff for the manufactures.

Its possible a tech call to a couple adhesive mfg's. and what I can recall with a few searches way back is that many super adhesives were using a heat applied system or a 2 part in the factory setting videos.

These companies also had listed other part numbers so with a bit more looking its sure possible to find something, I will keep an eye out for something.

It may still be recommended to have a mechanical fastener of some rating, you know how that goes, not many engineers signing off there.

One would have to just consider that auto bodys have to have a tac weld or other fastener, yet the fiberglass hoods I have dealt with are completely glued as I seen. go figure!

hey thanks for the better picture of the project, good luck
Floyd

bevans6 · July 04, 2016, 12:01:27 PM

I've been trying to understand what you are doing. MCI roof is 2" thick. Do you have a dropped ceiling/raised roof situation? Or are you planning to build roof top boxes and stick the cassette up through the roof and stick out the top. If the latter, I would tig weld up a box of .100" aluminium with a flange all around it, curved to fit the roof top perfectly, and use double-sided tape and blind rivets to hold the box to the roof, and mount the cassette inside that. You can get blind rivets that are leak-proof with a solid end. If I was to do this I would guarantee that it would not leak. The construction method is very similar to how they build tractor trailers these days.

ArtGill · July 04, 2016, 06:34:25 PM

Yes, the cassette will extend above the roof. My plan is to construct a box with a lip. The base plate that I want to install on the roof water tight. The base plate will have edge of 1 x 1 inch square rod that is welded on to make it ridged. At the width of the base plate my roof only has 1/8 of inch roll off on each side that I hope to fill with some adhesive. I plan to attach the box to the base using bolts or studs, a rubber gasket, and that allows the box to be removed for maintenance.