Hot hot hot aluminum!

[luvoldstuff]

Does that foil/bubble wrap type insulation work???
It was 95 degrees yesterday here in florida, I have a 12000 btu portable Ac that I was going to build a closet around, it vents through the floor, keeping the vintage look. I was working on bulkheads in the AS(19ft. '68 Globetrotter), and I was about to burn up, THE INTERIOR WON'T COOL OFF!!! I have new aluminum on the ceilings and walls, and the original insulation (replaced it where needed). You could not keep your hand on the ceiling, it was scorching hot!! You could watch the temp go from 84 to 91 in about 10 minutes inside when the sun would pop out,
In full sun, the temp would not go below 87. The AC unit was blowing hard and cold, it will cool it off when the sun is not out for a while down to 72(still 90 out). Can you say solar oven?
I am going pull the roof panels down (4X10) and add some insulation today. Luckily I didn't fully rivet them yet.
I know it will be a little better when I add cabinets and stuff and I will go to a 15k roof air if I have to, but I don't think it would help much with 150+ degree ceiling panels??!! A 12k should cool 17 ft.?
Any comments or suggestions on types of insulation I should add?
I was going to add 2 layers of that foil bubble stuff, maybe sandwiching the fiberglass???? I've got to do something. We mostly camp at the beach or lake with no shade.

[Silverflames]

Collin Hyde on the VAP uses the foil bubble wrap, then a layer of the pink fiberglass. I have read here on the forums it works well from others that have used it. I have done the same thing when I pulled down panels, but have not done the roof areas. But it should work well, give it works like the manufacturer stats.

Others have talked about a layer of material between the ribs and inside skin, that could limit the heat transfer between the metals.

[luvoldstuff]

A lot of good reviews about "reflectix" insulation on the Lowes website, they sound legitimate, 2 or 3 say they had a 15 to 20 degree drop in 140 degree attics. I'm going to get some right now I'll check back before I install it.

[lewster]

Coating your roof white will go a long way to helping your problem.

[Protagonist]

Insulating an aluminum trailer is always a problem.

Reflectix probably won't help as much as you hope, especially if the metal gets ver hot. Reflectix only has an R-value of about R-1 per layer, and a double layer only increases that to R-1.1.

Pink fiberglass is good, but you have to be careful NOT to compress it because the R-value is reduced if you compress it. If you've got a space two inches thick to insulate, don't try to squeeze a 6" layer of fiberglass into it. Your best bet might be Owens-Corning EcoTouch insulation for flexible ductwork. That will come in thinner layers and smaller rolls that are easier to handle. The thinnest available is 1-1/8-inch, which has an R-value of R-4.2.

Styrofoam insulation is a pretty good bet, too, though you may have to cut it into sections to fit it around curves. Get the blue Styrofoam Thermax® at Home Depot, in whatever thickness will fit in your walls. A mere half-inch thickness will be about R-3.3, or three times the R-value of a double layer of Reflectix, and thicker panels will provide more R-value.

Another thing that will help is a low-emissivity film on the glass. To keep heat out, you need to coat the OUTSIDE of the glass. The low-e film will get hot to the touch, because the heat that would be transmitted through the glass is absorbed by the film instead, but the interior will stay cooler.

On edit - Going along with Lewster, who definitely knows what he's talking about, a good choice for roof coating would be Henry SolarFlex, which is specifically designed for coating metal roofs, and available at Home Depot. While coating your roof, you might want to coat your air conditioner shroud, too. Even if it doesn't help your air conditioner work more efficiently, it will help extend the life of the plastic shroud, which suffers from UV exposure.

[reinergirl]

Originally Posted by Silverflames

Collin Hyde on the VAP uses the foil bubble wrap, then a layer of the pink fiberglass. I have read here on the forums it works well from others that have used it. I have done the same thing when I pulled down panels, but have not done the roof areas. But it should work well, give it works like the manufacturer stats.

Others have talked about a layer of material between the ribs and inside skin, that could limit the heat transfer between the metals.

Colin has switched to using Prodex, do a search here on the forums plenty of info . It's expensive but claims to have an r value of 16.

[luvoldstuff]

Isn't reflectix roughly the same as prodex.....or what is the difference? It "looks" the same(silver bubble wrap)? Maybe not, just wondering-I'm going with it already started cutting, would like the info though.....I know reflectix made a huge difference in my pickup.....oh well

[Silverflames]

Originally Posted by reinergirl

Colin has switched to using Prodex, do a search here on the forums plenty of info . It's expensive but claims to have an r value of 16.

Ahh good looking stuff. Might be hard to get your hands on, on short notice. Good to keep in mind.

Also the fiberglass stuff can be pulled apart to make it less thick. So the question is should you loose r value by compressing it, or loose r value by making it half as thick. The later I would guess.

[Silverflames]

I just found some on eBay. R vale of 11.5, $500 for 1000 sqf.

[Protagonist]

Originally Posted by luvoldstuff

Isn't reflectix roughly the same as prodex.....or what is the difference? It "looks" the same(silver bubble wrap)? Maybe not, just wondering-I'm going with it already started cutting, would like the info though.....I know reflectix made a huge difference in my pickup.....oh well

I wasn't familiar with Prodex, but this thread made me go to the manufacturer's web page and do a bit of reading. Looks like good stuff, especially the AD10. The AD5 has an R-value of 15, the AD10 has an R-value of 21. That's way better than any of the options I came up with. I'll have to keep Prodex in mind the next time I need to insulate something.

Prodex isn't really much like Reflectix. Reflectix is basically bubble wrap sandwiched between two reflective metalized plastic films. Prodex is actual closed-cell foam insulation, sandwiched between two layers of polyethylene, all that sandwiched between two layers of aluminum foil.

[jdalrymple]

A thermal break of some kind between the ribs and interior skins would be a great help too.

Maybe cork?

JD

[HiHoAgRV]

Originally Posted by jdalrymple

A thermal break of some kind between the ribs and interior skins would be a great help too.

Maybe cork?

JD

I used Prodex for the thermal break. 1 layer against the outer skin, the second layer covered everything except the windows. The inner skins are riveted to the ribs with the prodex in between.

[Silverflames]

Originally Posted by HiHoAgRV

I used Prodex for the thermal break. 1 layer against the outer skin, the second layer covered everything except the windows. The inner skins are riveted to the ribs with the prodex in between.

That's a great idea! Do you have any pics of it? Was it had to get the rivets to hold the skins on? I assume you used longer rivets?

[HiHoAgRV]

Originally Posted by Silverflames

That's a great idea! Do you have any pics of it? Was it had to get the rivets to hold the skins on? I assume you used longer rivets?

Here is the tryout:

http://www.airforums.com/forums/f109...ml#post1051687

And here is the start. Note that on afew sheets, I attached the prodex to the back of the aluminum, such as this photo.

http://www.airforums.com/forums/f109...ml#post1075324

[luvoldstuff]

Well two layers of reflectix up over the fiberglass, prodex too far away and too pricey for now. I think the transfer of heat from the ribs to the inner skin is the culprit-you can't touch the hot ribs hardly, just for kicks I put two layers of masking tape on the ribs, only took about 10
mins. you can actually touch them now??? probably won't do much.... already a difference with the new layers but still warm inside, I think once stuff-closets cushions, etc) get installed there will be less space and more cooled off things to help retain some coolness, I'll report back.

[Silverflames]

You can get rubber roofing tape used to help seal valleys and ridges. It's about 4" wide and sticky on one side. I wonder if that would be a good insulator between the ribs and inside skins?

[jcanavera]

Originally Posted by luvoldstuff

Does that foil/bubble wrap type insulation work???
It was 95 degrees yesterday here in florida, I have a 12000 btu portable Ac that I was going to build a closet around, it vents through the floor, keeping the vintage look. I was working on bulkheads in the AS(19ft. '68 Globetrotter), and I was about to burn up, THE INTERIOR WON'T COOL OFF!!! I have new aluminum on the ceilings and walls, and the original insulation (replaced it where needed). You could not keep your hand on the ceiling, it was scorching hot!! You could watch the temp go from 84 to 91 in about 10 minutes inside when the sun would pop out,
In full sun, the temp would not go below 87. The AC unit was blowing hard and cold, it will cool it off when the sun is not out for a while down to 72(still 90 out). Can you say solar oven?
I am going pull the roof panels down (4X10) and add some insulation today. Luckily I didn't fully rivet them yet.
I know it will be a little better when I add cabinets and stuff and I will go to a 15k roof air if I have to, but I don't think it would help much with 150+ degree ceiling panels??!! A 12k should cool 17 ft.?
Any comments or suggestions on types of insulation I should add?
I was going to add 2 layers of that foil bubble stuff, maybe sandwiching the fiberglass???? I've got to do something. We mostly camp at the beach or lake with no shade.

I'm no help on the insulation but sometimes it comes down to having enough BTU's to overcome the heat load. I've used those portable units at work and while you would think they have enough BTU's, I've always found them lacking in equaling the cooling efficiency of dedicated units.

I remember my introduction to Airstreaming with my 27' 2001 Safari. It had a 13.5K BTU Penguin and in its first outing in full sun 104 degree heat, my indoor temp was between 85-87 degrees. Awnings help and since the Safari only had a curb side awning, I sprung for a long street side Zip Dee. That helped more than you think.

When I got the 30' Classic I took the 15K option. Never have had a heat problem since, and full sun in the summer always means deployment of all the awnings. Anything you can do to keep that sun off the skin is going to be a benefit.


Jack

[Belegedhel]

I would second the above response. I have had some experience with these portable units, and they are typically so flawed in their design that you have no hope of ever achieving their rated performance. In 9 out of 10 different models, the unit sits in your living room merrily blowing out cool air from the front. But it is simultaneously sucking in air from the room, circulating it past the condenser coils, and blowing it out the window. Simple mass balance dictates that if I blow the air I am cooling out the "exhaust" port of the unit, then naturally, the room will have to draw in the same volume of air (which will have to come from someplace hot) in order to avoid creating a vacuum. There is the occasional unit that draws in air from outside, circulates it past the condenser, and then exhausts it. Problem with this is that the intake and exhaust ports will end up next to one another, and you are going to lose efficiency by using heated air to try to cool your unit.

So have a good look at the way your unit circulates air past the condenser. If there isn't an intake port as well as an exhaust port, then it falls in that 9 out of 10 category above. If it has two ports, then try drawing air in from underneath the trailer, and exhausting it out the side. At the end of the day, an 11000 BTU unit is still pretty weak, even if it did work as imagined.

I have read many discussions about insulation on the forums, and I always feel like we are trying to fight physics (ie., you are living in a very conductive hot-box) with extremely sophisticated and expensive insulating techniques. The money that is spent on the ceramic nano-spheres, and other space-age novelties could be better spent on a bigger AC that achieves brute force cooling.

Many of the radiant barrier reflectex type insulators have very little R value, and their main function is bouncing radiant heat. If you read the installation instructions, you find that if they don't have something like a minimum 1/2" air gap then their effectiveness is greatly reduced, or negated entirely. So sandwiching it between your skin and a bunch of pink stuff is probably just a waste of time and money.

Good luck!

[DavidsonOverlander]

Check out Page 5 of the Shell off headroom epiphany thread by Darkspeed for information on HSC-1000 Ceramic. Looks like an interesting product, but unfortunately there hasn't been anything new from Darkspeed in more that a year.

[FC7039]

Originally Posted by DavidsonOverlander

Check out Page 5 of the Shell off headroom epiphany thread by Darkspeed for information on HSC-1000 Ceramic. Looks like an interesting product, but unfortunately there hasn't been anything new from Darkspeed in more that a year.

Painting your aluminum (inside the walls) will increase the radiant heat. Aluminum is a not good radiator but paint is.

I tested the stuff.

My tests are in this thread.