A/C design on lite weight Update:April 14, 2013

[Maniac H3]

This is my sophomore attempt. It began in the summer of 2007 when I found myself with a lot of extra time on my hands. I was able to design, map out A/C ideas, wire and construct the trailer and frame in all the major components during that summer. August 2007, started Grad school and began dating my future wife, so the project sat and was moved around the shop and garage for the next four years while finishing school, getting married, buying and remoldeling a house. During 2012 Christmas break; I started back with some work on the 12 volt system, 110v, an A/C setup. Most recently, I constructed a sheet metal cowl to hook up the register (4”X10”) for the A/C supply, and a register (6”x10”) for a filter system and return. At night the galley will be closed and become the return duct. Still a lot of work to do, it is finally coming together. Now with a family of five, I am plannig on storing all of our camping stuff in the trailer and use it for bugging out, or camping/ fishing trips with my oldest son who will be 3 in May.

[Maniac H3]

Update March 24, 2013
Mocked up the duct today, closed the galley, and let the A/C run for about 5 minutes.... The cabin was cool even on the 84 degree day and the A/C was already pulling the 85% humidity out of the air....

Maniac

[mezmo]

Just curious as to how/where the air is drawn from
that you are cooling and then sending through your
duct into the cabin. Is that white frame with the blue
[fabric ?] in it the return air vent with a filter ?

Cheers,
Norm/mezmo

[Maniac H3]

There is a piece of 90 degree duct missing in the picture on the supply/positive pressure side. I wanted to show the mockup… once it is ducted into the sleeping cabin the air pressure will force it through filtered exhaust register on the left side of the picture. The filters are to keep bugs out during times the galley hatch is up. During sleeping hours, the hatch will be closed and the bottom half of the galley will act as return duct. This will allow the A/C to work more efficiently with fewer chances of icing up. The only time the A/C will not be pulling cabin air into the return is when the galley lid is up during that initial startup/ cool down period before bed. This design also allows for the noise level to be cut in half having it outside the sleeping cabin.
Maniac

[mezmo]

That's a good approach, especially with its helping with noise
reduction. Of course [stating the obvious] anyone using this
good set up needs to not have their cook stove [potential
fumes] in the galley. From the looks of your galley you
must use your stove on an auxiliary stand or use the end of the
picnic table etc..

Cheers,
Norm/mezmo

[Maniac H3]

Finished Duct..... Minus a little rustoleum leak seal to mantain to angles/geometry of the 90's, and some light insulation due to the sweating.
Maniac

[bobhenry]

If you continue to have problems with the adjustable elbows getting out of alignment a liberal coating of autobody undercoating will keep all in place and should help a bit with the sweating.

[lancew]

in the hvac industry we just used foil tape to seal up and hold the elbows. some like to put a self tapping screw where the joint is. wrap with insulation like you said. good luck hope it works well for you.

[Maniac H3]

Thanks for the input..... My father was a "ducts-man" in the days long before "round-duct", so I am sure he has some foil duct tape around... He was the one who helped me build the sheet metal cowl for the positive pressure side of the AC...
I was lucky he still had his sheet metal tools around...

Now.....possible Update to follow

Before I finish the trim work, I am thinking about removing everything and applying a silicone paint.... then reattach all the trim work with a silicone calk...

Current setup....... 1/4 inch plywood...Primer....white Elastomeric Roof Coating (dirt magnet)... High quality semigloss exterior latex...

I have not had any problem with the silicone calk Not sticking to the paint, so I am thinking it should not be a problem...

Any Thoughts?

Maniac

[working on it]

Maniac H3- I used similar ducting as you did, but mine is permanently mounted in the bulkhead between cabin and galley/storage. http://www.tnttt.com/viewtopic.php?f=21&t=54945 I used sheet metal screws to fix the outside ducts in place, insulated R-6 flexible ducting in between, covered the exposed metal on the Speedi-Boot 90 degree register vent boot with the same insulation, and foil-taped the heck out of it.