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Old 03-06-2014, 02:24 PM   #15
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Originally Posted by jdalrymple View Post
I understand the theory you are applying, but still wonder about true application.

Space under a black sunscreen is warmer than space under a light color, even with a fan moving air.

It would be interesting to see real data.


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JD
There are many assumptions that have to be made to do the calculations. Those such as volume of air moved through the condenser, the area exposed to sun, the max heat from the sun, the conduction and reflectivity of the plastic and so on. I made some of the assumptions and the worst case numbers I can come up with show less than a 1 degree effective temperature difference would be generated by a light vs dark cover. That is if it was 100 F outside a black cover would cause the air moving through the system to be 101 vs a white cover. My numbers all err on the conservative side, that is making it as bad as I can come up with. I would be very surprised if you could measure any difference in the field using expensive temperature measuring devices.

And without going into a college level course on heat transfer, I will not defend my answer with my assumptions and math calculations....LOL. I can only say "trust me" and duck.
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Old 03-06-2014, 02:35 PM   #16
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Thanks for the info so far. How bout the size... anyone regret spending more on low profile vs. standard height?

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Old 03-06-2014, 09:56 PM   #17
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Going back to the question of a black shroud. It seems like the biggest impact could be during the initial use of the day. I'm thinking that the +/- 100 lbs of refer up on the roof would get hotter under a black shroud. When you first start it up you have to cool down many of the parts-- the starting temperature of the refrigerant, copper coils, fan motor, fan blades, steel structure, etc. And on a moderate temperature day, where the unit cycles off 10-15 minutes at a time, wouldn't it have to do it all over again? Too bad I tossed my old cracked shroud when I got a new one. Could have painted it black and done some real world testing!
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Old 03-06-2014, 10:32 PM   #18
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Can't Make Up My Mind on an AC Unit

The only part where accumulated heat will matter at all is the condenser.

Being that the condenser is made to effectively discharge heat as quickly and efficiently as possible.....

Well I say authoritatively that the difference between a black cover and a white cover is essentially nil.

Incidentally, on well designed units the condenser sits just inside the shroud. Air enters the unit with virtually no contact with the shroud, making the temperature of the shroud 99.99 percent moot.

I suppose some heat might be captured in the unit and radiate into the interior, this would be minimal, and I doubt that this would would influence cabin temperature a fraction as much as a closed window.
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Old 03-09-2014, 08:24 AM   #19
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Originally Posted by idroba View Post
There are many assumptions that have to be made to do the calculations. Those such as volume of air moved through the condenser, the area exposed to sun, the max heat from the sun, the conduction and reflectivity of the plastic and so on. I made some of the assumptions and the worst case numbers I can come up with show less than a 1 degree effective temperature difference would be generated by a light vs dark cover. That is if it was 100 F outside a black cover would cause the air moving through the system to be 101 vs a white cover. My numbers all err on the conservative side, that is making it as bad as I can come up with. I would be very surprised if you could measure any difference in the field using expensive temperature measuring devices.

And without going into a college level course on heat transfer, I will not defend my answer with my assumptions and math calculations....LOL. I can only say "trust me" and duck.


I too ran some numbers on the subject, and came up with a bit more heat production than you mention. But, I concede that it may not make as much difference as I might have thought.


Lots of folks go to college to study all manor of subjects. It makes for a more well rounded world.

Regards,

JD
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Old 03-09-2014, 09:18 AM   #20
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If you have to paint the shroud black leave the top of it white. The operation of the unit probably won't care what color the shroud is but when it sits 99% of the time, that extra heat will age the electrical components. The sun can put out as much as 1400 W of heat per square meter. If you paint the top of the cover black, most of that heat will go into heating that AC unit and the components inside. Most of which are made of plastic of some sort. The fan motor bearings will most likely dry up with constant heat. Capacitors will fail sooner. The shroud itself may become brittle and crack from the heat. Or in some cases it might melt if it is made from thermoplastic.

Perry
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Old 03-09-2014, 11:50 AM   #21
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Perry, good points, that had not been previously mentioned in this discussion. I'm still wondering just how much hotter the components would get when some natural convection/outside air movement could remove it. Darn, I wish I had saved my old cracked shroud and could put this to a test!
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Old 03-09-2014, 01:31 PM   #22
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You could put a radiation barrier on the inside to reflect the heat back out but you better have a fiberglass cover instead of the ones made of polyethylene.

Perry
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Old 03-16-2014, 10:45 PM   #23
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Well, this Airstream will be in southeastern Washington, which has 300+ days of sun each year and is hot June through September. The AC will be needed all day starting early so I'm not worried about it sitting in the sun baking before it gets used that day.

Also, wouldn't the black shroud be a known issue if there was indeed an issue? Seems they wouldn't offer the black shroud if it caused problems?

Regardless, I went with the Penguin II and plan to paint it dark gray or black.

Thanks for the tips all.

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Old 03-17-2014, 09:23 PM   #24
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Ok, so one more question regarding the Penguin II. I have been searching the archives for about an hour trying to find this out but can't find a clear answer. I purchased only the top unit and ADB from American RV Company - no drain/drip device of any type. Is either a drain pan or drip kit for the Penguin II 13.5K absolutely required in order to install it? If I don't have either, will the gasket that is on the underside of the top unit not seal? Sorry if this is a stupid question. If it is, I'm game for a stupid answer.
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Old 03-17-2014, 10:51 PM   #25
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It won't drain through the drain line( which runs between your skins and out through the belly pan) unless you use the pan or cup system. We ordered our cup system separately from out of doors mart. I recommend it! It is easy to put in when you install the AC and otherwise the condensate runs all over the to and down the sides of your trailer.
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Old 03-18-2014, 05:30 AM   #26
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congrats on the order of the penguin II. We just replaced our Carrier that was only six years old with a new 15K HP. ODM did all the work and it looks great. We use small heaters and the propane furnace when over in the mountains, but it will be nice when the temps drop just for a system that keeps the temp where we want it.

We also upgraded with 3-fantastic vents this year. All of these items allow us to use our 3500 Kw generator if needed and allowed of course. Wouldn't want to upset any folks now would we as we relax in our 40+ old coach's, would we?

I don't think you will regret the purchase. Have fun and enjoy.
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Old 03-25-2014, 10:45 PM   #27
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All done. I threw caution to the wind and went with black Krylon paint.
I must have been drinking heavily while working on it since I didn't think about painting the drain cups, so they stick out like a sore thumb to me. I'll get back up there and brush paint those. Had to install a drain hose in the interior as well.

A $5 can of primer and two $6 cans of black paint sure beats paying over $300 more for the black version from the factory.

Thanks for the suggestions.
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Old 03-26-2014, 12:25 AM   #28
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It looks nice, good choice!

Btw, that is a great looking trailer... <envy>.
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