Fridge Covers, they ARE arse about

Submitted: Thursday, Mar 19, 2009 at 21:11
ThreadID: 66992 Views:3001 Replies:15 FollowUps:12
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My fridge has been sitting outside for the last 5 days and is exposed to sun.

I've always reckoned the shiny/foil side should be on the outside to reflect the heat. The other theory is that that foil inside reflects the cold.

BOLLOCKS.

When my fridge has been in the sun, I have reached in under the cover and the lid of the fridge is hot.

Sure, at night the foil on the inside may help keep it cold, but it is durfing the heat of the day that the fridge works hardest.

Jim.

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Reply By: PradOz - Thursday, Mar 19, 2009 at 21:15

Thursday, Mar 19, 2009 at 21:15
why not do a test?? check temp with cover as is. then wrap all in alfoil - over the cover - and check temp. maybe better to just not leave fridge in sun if possible
AnswerID: 354998

Follow Up By: PradOz - Thursday, Mar 19, 2009 at 21:20

Thursday, Mar 19, 2009 at 21:20
i also have a cover on my fridge and i usually place one of those silver windscreen covers over it loosely and have noticed it keeps cooler easier. it is a spare old one i had and easily folds over top and hangs down each side to keep sun/heat off
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Follow Up By: Best Off Road - Thursday, Mar 19, 2009 at 21:23

Thursday, Mar 19, 2009 at 21:23
UM, the fridge would not be in the sun if it wasn't necessary.

Shouldn't be a need to put a windscreen cover over it if it was designed correctly.

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FollowupID: 623078

Follow Up By: robertbruce - Thursday, Mar 19, 2009 at 21:50

Thursday, Mar 19, 2009 at 21:50
they are black so you can be even "more cooler" when you buy more panels, batteries and suspension upgrades etc.....
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Follow Up By: Steve - Thursday, Mar 19, 2009 at 21:55

Thursday, Mar 19, 2009 at 21:55
ha - clearly not impressed Jimbo :)))

I can see your logic and have never gone for one of those covers. In fact, I do exactly what the other guy said. If you have to park the fridge in the sun, a window shade is best with a bungee strap holding it - not a trendy look but at least some air can circulate. Then again, I'm too tight to pay for one of them expensive covers
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Reply By: Robin Miller - Thursday, Mar 19, 2009 at 22:05

Thursday, Mar 19, 2009 at 22:05
Hi Jim

It makes little difference particularly as the cover gets older
and there is a specific saftey reason for the dull surface being on the outside.

That reason is that it doesn't cause a dangerous reflection into
drivers eyes.
For the same reason building sisalation is now dull on the outside(and also builders can get sunburn from it).

As for the heat reflection , it also works on heat being emitted from a surface,including the inside surface.
The emission is proportional to the smoothness of the surface and over time an outside surface gets roughened up causing a loss of efficentcy.

The fact that the air is hot between the inner layers is not ideal but its also not as bad as it seems because the warm air has little thermal mass as doesn't pass the heat thru readily.
Robin Miller

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AnswerID: 355022

Reply By: Member - Matt M (ACT) - Thursday, Mar 19, 2009 at 22:07

Thursday, Mar 19, 2009 at 22:07
Jim,

I agree with you, never been able to work that one out myself. Its like roof insulation, shiny side up - reflects the heat away, dark side down - absorbs heat form the roof space.

Foil doesn't keep it colder at night, it still reflects any trapped heat back to the fridge and stops it escaping for longer. Same way a space blanket works.

Maybe its just a fashion thing.

Matt.
AnswerID: 355025

Reply By: Member - Mfewster(SA) - Thursday, Mar 19, 2009 at 22:22

Thursday, Mar 19, 2009 at 22:22
The silver side can't "block cold in". Heat always moves from hot to cold, so therefore the shiny side should be out, but as heat is simply energy and their are different types, silver is only effective in reflecting some types of heat ie, sunrays. As far as I can see, silver side only doing its thing if the fridge and cover are in direct sunlight. In the back of a covered vehicle where the heat is coming from air temp, the silver will heat up as much as any other material. What matters then is the insulating factor of the layers, that is, the rate at which heat can through the layers. If it is hotter outside the fridge than in, heat will continue to move through the layers (including the fridge case) until the temp inside of the fridge balances with the temp outside. The thicker and higher insulation factor of the layers, the slower heat can move through to do its balancing trick. The fridge motor removes heat from inside the fridge and dumps it into the air outside the fridge.
AnswerID: 355030

Reply By: Off-track - Thursday, Mar 19, 2009 at 22:30

Thursday, Mar 19, 2009 at 22:30
And to get an even better efficiency you could paint your fridge black - as long as the surface is not in direct sunlight.
AnswerID: 355034

Follow Up By: Member - Matt M (ACT) - Friday, Mar 20, 2009 at 07:54

Friday, Mar 20, 2009 at 07:54
Don't agree mate. The black will still absorb heat (non-visible spectrum) faster than a shiny or reflective surface.

Put two pots in an oven, one silver and one black, and the black one will heat its contents faster. No visible light, just radiant heat.

Matt.
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Follow Up By: Member - Mike DID - Friday, Mar 20, 2009 at 21:20

Friday, Mar 20, 2009 at 21:20
Ever seen a black refrigerated van or cool-room ?
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Follow Up By: Shaker - Friday, Mar 20, 2009 at 23:17

Friday, Mar 20, 2009 at 23:17
If you paint VW engine covers white, they overheat!
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Reply By: Muddy doe (SA) - Thursday, Mar 19, 2009 at 22:51

Thursday, Mar 19, 2009 at 22:51
I can see that having the silver side out might help reflect the sun's rays and heat energy away from the fridge but there is one possible issue. I think I would need a welding helmet to get anywhere near it to get a beer out on a bright sunny day!

Cheers
Muddy
AnswerID: 355040

Follow Up By: Bonz (Vic) - Thoughtfully- Friday, Mar 20, 2009 at 21:08

Friday, Mar 20, 2009 at 21:08
you'd be able to find it at night tho
.
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Reply By: Totaltip - Thursday, Mar 19, 2009 at 23:21

Thursday, Mar 19, 2009 at 23:21
Hello Jim and the Forum,

I use a refridgerated Transit van for work, drive long distance with fridge on 2-3 degrees. The rear fridge section is fully insulated, and in my opinion well insulated, it has to be.
When I stop, the outside of the vehicle (the fridge part) is cool to touch, sides, roof, doors, all cool, even on a very hot day like 40 degrees.

So if we consider this to be a big car fridge, then if a cover was put on it, the cover would have the reflective silver stuff on the inside to reflect to coolness back in, and that is probably why our car fridges have it on the inside. Keeping coolness in rather than the ambient temperature out.

The idea of covering with a reflective windscreen cover works too because it does minimise the ambient heat entering the cabinet, as does parking it in the shade, covering with a blanket, or operating it at night or overcast days, it does make a difference.

My point is maybe the covers are designed to keep coolness in rather than heat out.

Remember the heat from within the cabinet is taken out by the system and pumped out into the car via the vent in the compressor containment. If your car is not able to let this heat out it is then adding to the ambient temperature around the fridge.

Cheers
AnswerID: 355048

Follow Up By: ross - Thursday, Mar 19, 2009 at 23:37

Thursday, Mar 19, 2009 at 23:37
"the cover would have the reflective silver stuff on the inside to reflect to coolness back in'


You can reflect coolness ! LOL

I dont think even the Fonz could do that.

I think the foil maybe a moisture/air barrier like they wrap people in to keep them warm after exposure.
I think the foil also has perforations ,possible to allow some breathing between inner and outer
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FollowupID: 623108

Reply By: Hairy (NT) - Friday, Mar 20, 2009 at 00:56

Friday, Mar 20, 2009 at 00:56
Hey Jim.....
Pick up a piece of foil.........look at it.......... and then turn it over.........SPOOKY HEY..........Same $hiit both sides????????

Theory is........whats out stays out, whats in stays in.....( a little longer)

Cheers
AnswerID: 355057

Follow Up By: Member - Matt M (ACT) - Friday, Mar 20, 2009 at 07:59

Friday, Mar 20, 2009 at 07:59
Actually Hairy, if you turn it over you will see they are different. One side shinier than the other. Put the shiny side on the inside and it will keep your food warm for longer because it does a better job of reflecting heat back into the food.

Matt.
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Follow Up By: Hairy (NT) - Friday, Mar 20, 2009 at 11:16

Friday, Mar 20, 2009 at 11:16
So if that theory is right.....sisolation put in houses doesnt work?
Because one side is painted blue (non reflective) and the other side is in a dark roof space hidden by your ceiling and covered in dust???? Some how I dont think you would convice CSR or any other manufacturers..........
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Reply By: handy - Friday, Mar 20, 2009 at 07:40

Friday, Mar 20, 2009 at 07:40
explain a survival blanket then, silver stuff on the outside. ????
AnswerID: 355064

Reply By: greenant - Friday, Mar 20, 2009 at 09:10

Friday, Mar 20, 2009 at 09:10
Shiney in shiney out why is a car radiator painted black then

Greenant
AnswerID: 355079

Reply By: Member Brian (Gold Coast) - Friday, Mar 20, 2009 at 09:17

Friday, Mar 20, 2009 at 09:17
trailblaza.....

No bag required!

Simple.

Cheers

Brian
AnswerID: 355082

Reply By: Member - Keith C (NSW) - Friday, Mar 20, 2009 at 09:26

Friday, Mar 20, 2009 at 09:26
G/day Jim,Strewth,you sure know how to get a thread going,It must be those old farts yer camping with.Thanks again for your help the other day.I hope you`re making a quid. Regards Keith C
AnswerID: 355085

Follow Up By: Best Off Road - Friday, Mar 20, 2009 at 19:57

Friday, Mar 20, 2009 at 19:57
Keith,

Making a good quid, great exosure too.

Gets a bit boring though. The forum is helpinf=g kep me sane at night.

Cheers,

Jim.

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FollowupID: 623243

Reply By: Member - Mike DID - Friday, Mar 20, 2009 at 21:27

Friday, Mar 20, 2009 at 21:27
If you have an object hotter than its surroundings and you want it to cool down, paint it black, it radiates heat better than silver does.

If you have an object cooler than its surroundings and you want to keep it cool, paint it silver, it will reflect the surrounding heat away.

This only applies to air interfaces because its about radiation. Two surfaces in contact with each other are controlled by conduction, not radiation.
AnswerID: 355222

Reply By: Shaker - Friday, Mar 20, 2009 at 23:18

Friday, Mar 20, 2009 at 23:18
Why is the reflective side of sarking on the inside when it is wrapped around a house?
AnswerID: 355241

Reply By: Oldsquizzy (Kununurra) - Saturday, Mar 21, 2009 at 05:20

Saturday, Mar 21, 2009 at 05:20
If a single reflective surface is used alone and faces an open space, it is called a radiant barrier. Which is a reflective insulation.

When it faces inward it is thermal resistance insulation measured as a R-value which is a resistance to heat flow. The greater the R-value the better it insulates.


AnswerID: 355257

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