I think the idea of glueing foam to the bottom of the floor is a good idea too. The good news is that the floor is the least important place to have insulation so most any solution would work well enough in my opinion. Some forum memebers have even elected to leave the under floor area without any insulation.
Malcolm
I'm conflicted about this. I like your idea of foil with a hole in the center. When I get the belly pan off, I'll evaluate this possibility. My problem is that even though I mostly worry about surviving the 100+ days in the dessert, there are those pesky days in the winter when all of al sudden it's 5 degrees outside and I fret fret fret about my copper pipes that sit right on the floor. So I think belly pan insulation is required.
I think I agree with you that some insulation is needed for the plumbing if it is going to be exposed to low temps for long times. I suppose that you might also be able to add insulation around the pipes themselves if there is sufficient clearance around them.
In any case once you have access to the under floor area it would be pretty easy to install virtually any kind of insulation. I would certainly think it would be fairly cheap insurance.
I wonder if others would like to build panels. We'll need to establish a standard size and thickness (1-1/2", right?) if there is a lot of interest.
Looks like the standard will be 12" square by 1-1/2" thick. I'll test six panels simultaneously and publish the graphs for as many test items as I get in-hand. Target date for testing would be the first week of June, so get your panel proposals in!
Panels I'd like to suggest:
1. Single sheet of aluminum (a possible worst case standard)
2. Two sheets of aluminum separated by 1-1/2" and only air inside
3. #2 filled with 2" spun glass (vintage trailer standard)
4. #3 with 3" length of rib riveted in the center (this would provide about 4% rib area--attempt to duplicate real vintage trailer construction). (two inside temps would be measured, one near edge and one at the rib location)
5. #2 with suspended foil and bubble insulation, sealed at edges
6. #2 with top sheet painted outside with white roof thermal coating
7. #2 with top sheet painted inside with white roof thermal coating
8. #2 with some variety of solid foam fill
9. #5, but with two layers of foil, suspended from each other and from outside sheets
One combination that you might consider adding would be one that was painted on the outside. Maybe silver paint something like the way that Andy at Inland would paint it. While paint would not have as much of an insulation value as a roof coating it would have some. I eventually intend to paint my AS so I would like to know what the relative improvement would be compared to the plain aluminum that I now have.
Help! I need a "sample" of roof coating, Kool Seal White or any other suitable substitute (perhaps thick and rubbery, or whatever simulates what AS is using these days), to paint two 12x12" panels.
Also, need a piece of rib, as flat as possible like maybe from a section down near the floor) about 3" long. If I can't get a piece of real rib, I'll simulate with a piece of "U" channel. Anyone parting out a trailer and can spare a rib?
Malcolm--I can easily paint a panel, as you suggest. I may take one of panels 2, 3, or 4 and paint it for a second test run against the other panels. I'll use silver and black (not that anyone would do black outside).
I am really up for this test. It will be a real coup if we can show that painting the inside of the outer skin with a low emissivity paint is effective--for those of us with our interior skins off, it will allow improved thermal performance without a white outside. Yeah, polish all the way over the top, just what I look forward to every day!
well the factory is now using foil in the floors...
here is a photo....i offer as proof
do you suppose this is "instead of" pink stuff under the floor, or "in addition to"? I wonder what the R-value of a single layer of the bubble-foil is when simply stapled up against the plywood.....
This is a big project and a noble attempt to shed some scientific light on a practical problem.
I have one suggestion to make. When selecting colors for paint testing, make at least one a plain bright white on the outside, and compare it with the fancy stuff on the outside to match the current factory practice of painting the top of AS white to beat the heat.
The reason is to act as a control for the white hi-tech Kool-whatever coatings. I mention this because the folks running the monolithic dome institute site ( www.monolithic.com ) once tested a pair of small buildings side by side, one with a fancy-dan microsphere insulating paint the other plain white enamel, with a temperature logger inside each. The result? No measurable difference in performance between them.
One can't say in advance how a test will go with different products, different surfaces and different methods, but it would be a logical flaw to test the hi-tech substance only against black and uncoated aluminum and not account for the effect of mere color in blocking heat.
do you suppose this is "instead of" pink stuff under the floor, or "in addition to"? I wonder what the R-value of a single layer of the bubble-foil is when simply stapled up against the plywood.....
I hope it's 'in addition to'. As I recall, bubble foil has about 0.3 R-value.
__________________
There's a fine line between a hobby and a mental illness.
How are things going over at the various research labs?
i had a thought as i was looking through some of my shop. So the foil insulation needs air space right. Do we know the effect of that airspace being larger or smaller? how bout in a side to side measurement? as i was cleaning up i found a sheet of 1/2 in close cell foam that i had cut out a ton of 4in circles from, for another project. so what i am left with is a lattice of the the reverse. so i was thinking that something like this could be spray glued to the foil insulation and maybe even a laminate of a few layers of each? from what we know do you think of a sandwich of say two or three layers of the foil and therefor 3 or 4 layers of the lattice as a single unit then fit tightly in-between the ribs? do you think that the insulating factor would justify the man hours or cost? do you thing that there is a minimum airspace that thinner than that does not work? i know they recommend something like a inch or two, but i wonder what the minimum is and what relation the amount of air has to the final effectiveness?
My wife and I are as new to airstream as it gets. We towed our 78 Tradewind home last night, vin# 125D8SO967. Anything ,anyone knows about a 78 restoration would really help. We retire this year and have better than average skill and tooling but no knowlege of airstreams. In the past we have rebuilt : 2 Cessnas ,2 houses,2 houseboats,and a modest bank account. I'm thinking complete rebuild although,the rv is not in "too" bad a shape. We'd sure appreciate any info you might have. Thanks Folks , Mark & Trudy Lillard Williamstown ,Ky.
Looks like the standard will be 12" square by 1-1/2" thick. I'll test six panels simultaneously and publish the graphs for as many test items as I get in-hand. Target date for testing would be the first week of June, so get your panel proposals in!
Panels I'd like to suggest:
1. Single sheet of aluminum (a possible worst case standard)
2. Two sheets of aluminum separated by 1-1/2" and only air inside
3. #2 filled with 2" spun glass (vintage trailer standard)
4. #3 with 3" length of rib riveted in the center (this would provide about 4% rib area--attempt to duplicate real vintage trailer construction). (two inside temps would be measured, one near edge and one at the rib location)
5. #2 with suspended foil and bubble insulation, sealed at edges
6. #2 with top sheet painted outside with white roof thermal coating
7. #2 with top sheet painted inside with white roof thermal coating
8. #2 with some variety of solid foam fill
9. #5, but with two layers of foil, suspended from each other and from outside sheets
Others?
After a year of doing other things and letting the hot weather get by me (again), I've built the test fixture. It's glued up from 3/4" foam panels to achieve good isolation between the front and back of the test panels. The test panels slip into 1-1/2" deep wells in the face of the fixture and are taped in place to prevent air flow around them.
The test panels, #2, #3, and #5 from the list above, are made from 12" square sheets of .025 and .032 aluminum. The air-filled and one glass-filled panel are the .025, which is moderately polished. The panel with the silver bubble sheet (this particular insulation has two layers of bubbles between the silver mylar outside layers) and the other glass-filled panel are .032 mill finish (a striated finish with the grain clearly visible that creates the appearance of light sanding in one direction). The air-filled test panel should give a pretty powerful contrast in heat transfer compared to the others.
Why two glass-filled test panels? As soon as I put the other three out in the sun, a simple hand test of the surface temperature revealed that the mill finish was immediately warmer than the polished finish. The mill finish has about the same coarseness as a 25 year old shell that's lightly corroded. So I decided I needed a direct comparison between the bubble panel with the mill finish.
Heat transfer is going to be inferred from the back side temperatures of the panels. I will measure the front side temperature of the two glass-filled panels to see if my initial finding that the mill finish is hotter is actually born out by data.
I hope to get some data by the end of the week. If temperatures here in Colorado stay low, I'll use a heat lamp to get hot temp data. The cold data should come from the environment pretty soon now.
I have 6 additional 12" square cover sheets, enough for three test panels. If anyone has a construction they'd like to test after these first tests are done, let me know. I intend to paint one of the glass-filled panels white on the outside to see what effect that has. What paint should I use? I may paint the inside of the outside panel white on a future test--I think white is generally a good reflector, so it's excellent for the outside, and also a poor emitter, so it would also improve (reduce) heat transfer from the panel towards the inside.
Nice ZEPP!
My solar convection loop heater is just a bigger box!
I'll guess that you will see temps behind the glass at temps over 140 F. That would simulate the windows on the trailer. I use reflectix in my windows in the sun facing windows to keep inside temps down.You are going to test glass aren't you?
I'm very interested in your test results.
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The state had no money
Almost everyone spoke spanish
There were gunfights in the street
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