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Minnie's Mate · 08-21-2004, 10:36 PM

Quote:

Originally Posted by mandolindave

I am surprized that the white was that much hotter too. Could it be that the
the reflection was adding to the temperature reading? I am wondering why
none of you tried the experiment with painted beer cans. ( just kidding )

P.S. Use the hot beer to boil hot dogs when you are finished ( to avoid
being accused of alcohol abuse ).

I'm no physisist or infrared thermographer, but I think mandolindave might have hit on the reason for the white having the high temperature but keeping the interior cooler. Airstream claims the white roof lowers the interior temperature by 7 degrees vs. mill finished aluminum. Infrared thermometers measure the radiant heat of an object by measuring the infrared heat being radiated or given off by that object. Since white reflects all light, including the light we cannot see, which includes the infrared spectrum, I believe the white paint is also reflecting the infrared heat of the sun and that it is being measured as part of the temperature the infrared thermometer "sees" on the white painted aluminum.

I know if you stand on a typical black built-up roof you get hot, but if you stand on a white PVC roof you get even hotter even though less heat is reaching into the interior of the building. The sun's heat is reflecting off of the roof and hitting you along with the direct sunlight from above so you get a compound heat effect. As far as the black rubber coating being cooler, you got me on that one!

Inland RV Center, In · 08-22-2004, 12:14 PM

Who wants to further the study I started?

Surely, there must be someone that has different test instruments than I do.

At this point, I can't offer any more information than previously posted.

If someone, who has additional test equipment, wants to continue the study, please let me know and I will send you the metal plates that I used.

Andy

pinkflamingoes · 08-22-2004, 01:11 PM

This whole thread was worth the Partridge Family airstream alone! Thanks Bredlo!

malconium · 08-22-2004, 01:32 PM

Andy,

I don't think that additional test instrumentation is needed. I really think all that is needed is to measure the temperature from the back side using an infrared thermometer like what you already have. If you don't have the time to do that my offer earlier in this post still stands. If you will send me your panels and a little bit of the 2" fiberglass (I tossed out all of mine) I will do some additional testing. I found that I can buy an inexpensive infrared thermometer at radio shack that should be sufficient and I am willing to do that.

Here is what I am prepared to do:

1.) Create a ladder like framework to mount the panels on out of 2x lumber. I can easily support the framework on some saw horses. The 2x lumber will create wall cavities that are 1-1/2" thick like on an AS.

2.) Attach the test panels to the top of framework.

3.) Add fiberglass insulation to all of the panels between the 2x lumber to represent the correct AS wall thickness. Add plain aluminum to the bottom side to represent the interior of an AS.

4.) Put the whole assembly out in the sun and measure the temperature from the bottom side of the panels as though it was inside of the AS.

5.) Change all of the insulation in all of the panels to foil insulation and take the readings again.

6.) Publish my findings.

What do you think?

Malcolm

Inland RV Center, In · 08-22-2004, 02:17 PM

Malcomb.

They will be on their way, tomorrow, via UPS.

Same address as before?

Andy

roger n cindy · 08-22-2004, 03:57 PM

RED, red red ! has anyone besides me ever thought about having the exterior of ther airstream engraved? ENGRAVED- scenes permanently scratched ( artisticly of course ) into the exterior ! angels , eagles , wolves and little deer frolicking ? mountains , praries ,deserts and of course an amber wave of grain ! just wondering, i guess paint would be easyier to remove if you didnt like it !
roger

norbert · 08-22-2004, 07:11 PM

Quote:

Originally Posted by roger n cindy

RED, red red ! has anyone besides me ever thought about having the exterior of ther airstream engraved? ENGRAVED- scenes permanently scratched ( artisticly of course ) into the exterior ! angels , eagles , wolves and little deer frolicking ? mountains , praries ,deserts and of course an amber wave of grain ! just wondering, i guess paint would be easyier to remove if you didnt like it !
roger

only if you have teresa kerrys money....

Anon · 08-22-2004, 09:43 PM

I have an Argosy Minuet that I need to paint sometime soon. I am going to try that PaintShop thing.
I do have to say that I have always been an Airstream purist. I have camped in nothing but Airstreams from the time I was born. My dad didn't even like the Argosys. When I would mention that I want one he would ask me why I wanted a an imitation Airstream.
Now you guys got me thinking! I was gonna paint it using the same DuPont Imron paint codes. Now I may change my mind!
Oh dear, what will happen when I join the WBCCI? I will have to be on the look-out for those scooters!

malconium · 08-23-2004, 12:21 PM

Andy,

My address is the same as for my orders. Please be sure to include some of the 2" fiberglass if you would please. As I mentioned I don't have any on hand and the 2" stuffs seems a little hard to find around here.

Thanks,

Malcolm

markdoane · 08-23-2004, 06:53 PM

Malcolm,

I see a problem with your test protocol.

Step 4. . . . . where are you going to find sunshine in Portland?

LOL. I applaud you efforts to move forward the boundaries of Airstream technology.

malconium · 08-24-2004, 12:01 AM

Don,

If all else fails I can put the test panels in front of the fireplace.

Malcolm

mandolindave · 08-24-2004, 05:16 AM

Malcolm,
I think an open air test will minimize the range in test results. I suggest
using a card board box with the top cut out and the panels covering the opening. Limit the airflow. Then take measurements inside the box.
Hey Andy, sorry for second quessing you. We just love to beat a topic to death around here. To us, it is all about fun, joy, and satisfaction. I know
how dedicated you are and how much time a business takes out of your
life. Thanks though for all the time that you give us anyway.

mandolindave · 08-24-2004, 01:33 PM

Hey All,
I have an even more better idea. I think the test should be done at a rally with real airstreams ( and an Argosy ) . Line up the trailers facing north ( so they will all get the same sunlight ), and far enough away from each other so they won't cast
a shadow on each other. Use an unpolished AS , a polished AS and a white Argosy.
( and maybe an S.O.B. ) Take similtaneous temperature readings hourly. No awnings allowed.

wahoonc · 08-24-2004, 05:48 PM

I have a non contact thermometer RayTek ST20 Pro If necessary I will make arrangements to duplicate the test. BUT! I have a 40' storage trailer with an aluminum top,it is parked in full sun. The front half has been coated with Kool Seal White Elastomeric On a 90 degree day there is a verifiable 10-12 degree temperature difference between the bare aluminum and the coated sections, measured on the inside of the unit.(Eventually I will finish the roof coating) Also FWIW I was playing with the thermometer in my AS the other day and noticed a 8-10 degree temp difference between the center of the interior panels and where they cross the ribs.

Guess no one ever considered using thermal breaks?

I do plan to coat the very top panel of my AS using the Kool Seal or a similar product. But I want to install my Fantastic fans first.

Aaron

DogHouse · 08-24-2004, 07:38 PM

Following is a website that shows how they test their radiant heat barrier product for effectiveness.

http://www.afs-foil.com/pages/hotbox.htm

malconium · 08-24-2004, 09:08 PM

Aaron,

My guess is that if the kool seal was on the inside of the outer skin that there would be an even better improvement. I still think the reason that a thick white coating reduces the interior temperature is not because white is a better reflecter but because the thick rubbery coating helps stop heat from conducting through the aluminum.

Malcolm

malconium · 08-24-2004, 09:13 PM

MandolinDave,

I can easily enough do something like what you suggest. My guess, though is that the readings for this type of test, with the heat source being mostly radiant, that the results might not be that much different. We shall see.

Malcolm

malconium · 08-24-2004, 09:17 PM

I bought a simple Infrared thermometer for the testing yesterday at Radio Shack. There was an in-store coupon that I found on the internet that gave me a 40% discount. With the necessary 12volt battery I paid about $35 total.

Just waiting for the panels to arrive from Andy now.

This is going to be an interesting project.

Malcolm

wahoonc · 08-25-2004, 03:53 AM

Quote:

Originally Posted by malconium

Aaron,

My guess is that if the kool seal was on the inside of the outer skin that there would be an even better improvement. I still think the reason that a thick white coating reduces the interior temperature is not because white is a better reflecter but because the thick rubbery coating helps stop heat from conducting through the aluminum.

Malcolm

Malcolm,
That is a part of it too. I work in the commercial roofing industry. One of our most energy efficent roofs is a White PVC membrane, and it gets HOT! on that roof in the summertime from the reflectivity of it, I have never bothered to measure the temps in comparison to some of the other systems. I also know that they are making an energy star rated metal panel also, where the paint is the key to the rating, and suprisingly enough the paint is a matte finish.

Aaron

malconium · 09-22-2004, 08:31 AM

I thought I would make a posting about the insulation test to let people know the project is not dead - just delayed.

I have had to leave home for a 1 week business trip and have not been able to work on it. I do have the panels and fiberglass inslulation that Andy sent me. I also have some aluminum I can use to make inner skins so I can build some sample panels with inner and out skins and insulation.

Hopefully I will be ready to take some measurements within a week or so, weather permitting.

I think when I post the results I will start a new thread that is more obviously about insulation issues so it might be more obvious what it is about.

Malcolm