Venting heat from rear tub

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GabrielSyler

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Chatswood NSW, Australia
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Looking for a few thoughts and ideas on heat management.

My fridge is in the rear tub of my vehicle. The tub is covered with a soft tonneau cover, most likely vinyl.

On a hot sunny day (30+ degree C) the tonneau cover gets too hot to touch which is baking the inside of the tub. The top of the fridge cover (about an inch clearance from the tonneau) reaches 80 degrees C and the front of the fridge cover reaches 60 degrees C. A couple of temp checks on random locations inside the tub are above 60 degrees C.

The insulated fridge cover only knocks off a few of degrees but the fridge maintains the set temp of 2 degrees. The downside is that the compressor works hard and I'm concerned that this will reduce its life. We haven't got to the real hot periods yet (high 30's) so I'm looking at options to reduce the temperature inside closer to ambient.

Parking in the shade isn't always possible and is also counter productive to my solar setup. I'd rather not remove the tonneau for security reasons and I'm not sure the direct sunlight on the fridge would be any better.

The fridge compressor is at the back of the tub and the tonneau cover does has a little "flap" which I open to help vent heat but it didn't appear to help that much. As per this pic.

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Idea 1 - Forced fan extraction
The compressor exhaust is closed to this flap (as in this photo). Has anybody had any experience using additional fans to move the air? I could place the fans adjacent to the compressor exhaust, or I could rig something facing upwards over the gap. Would I be better to have the fans suck cooler air in, or blow hot air out. Will this work or would I need fans to suck in and suck out similar to a computer system. I can get a couple of low current silent 12v 120mm fans which will move 1m3/min. They cost around $15-20 each.
20190102_122254.jpg

Idea 2 - Sunshade on top of tonneau cover
Whilst I wouldn't be able to use this whilst driving, when parked up I could put a windscreen sunshade on top of the cover. It works on a windscreen to reduce heat in the car so the principle should be the same. A XL one will cost $20 and would cover most of the tonneau.
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Idea 3 - Insulation underneath the tonneau cover
I could add insulation underneath the tonneau cover, I could use the sunshade or get a role of reflective insulation for $15. This would provide heat protection whilst driving.

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I could give all the above a try but I thought I'd see if any of these have been tried with success or what other people have done?

Thanks
 
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GabrielSyler

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Enthusiast III

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Chatswood NSW, Australia
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Hi Gabriel, I just came across your post (a year later!) as I'm facing the same problem. Did you ever find a solution?
Hey mate,

I tried the fan solution and whilst it did help circulate air inside the tub (for the benefit of the compressor) it didn't lower the top of the fridge being too hot to touch from the sun heating through the tonneau cover. Compared to just leaving the flaps open, I don't think it helped too much.

I tried adding more insulation between the fridge and under the tonneau cover. Australia sun is too powerful and it didn't really make much difference.

I tried using an external sunshade ($13 for 80cm x 180cm)and I just lay this on top of the tonneau cover when I'm parked up. It helps lower the heat in the tub significantly. You can now touch the top of the fridge. I'd say this is the solution. You could secure it to the tonneau (HD velcro?) if you wanted to drive with it on I suppose. But I'm only really concerned when parked up.

Hope that helps.


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Shahn

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Did you ever find a better solution? I'm running into this same issue. My compressor is working overtime due to the heat under the cover on hot trips.
 

GabrielSyler

Rank V
Launch Member

Enthusiast III

1,721
Chatswood NSW, Australia
Member #

13933

Did you ever find a better solution? I'm running into this same issue. My compressor is working overtime due to the heat under the cover on hot trips.
TBH the external sunshade did a pretty decent job. I ended up building a storage rack which sat about 200mm above the tub cover. I was able to fit the sunshade to the bottom of the rack and that helped keep the direct heat off. More so if the rack was loaded with equipment (Photo of rack below)

20200122_191910.jpg

I've since moved from that and have a solid lid which leave a gap between the surface of the lid and the fridge although the tub is better sealed now so will have to see how it goes.

ranger.jpg
 

Shahn

Rank VI
Member

Off-Road Ranger I

4,418
Snohomish County, WA, USA
First Name
Shahn
Last Name
Brown
Member #

29302

Ham/GMRS Callsign
GMRS - WRQD549
TBH the external sunshade did a pretty decent job. I ended up building a storage rack which sat about 200mm above the tub cover. I was able to fit the sunshade to the bottom of the rack and that helped keep the direct heat off. More so if the rack was loaded with equipment (Photo of rack below)

View attachment 204396

I've since moved from that and have a solid lid which leave a gap between the surface of the lid and the fridge although the tub is better sealed now so will have to see how it goes.

View attachment 204395
Awesome, thanks for the reply! I will for sure try the sunshade! :) Cheers!
 
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Shahn

Rank VI
Member

Off-Road Ranger I

4,418
Snohomish County, WA, USA
First Name
Shahn
Last Name
Brown
Member #

29302

Ham/GMRS Callsign
GMRS - WRQD549
TBH the external sunshade did a pretty decent job. I ended up building a storage rack which sat about 200mm above the tub cover. I was able to fit the sunshade to the bottom of the rack and that helped keep the direct heat off. More so if the rack was loaded with equipment (Photo of rack below)

View attachment 204396

I've since moved from that and have a solid lid which leave a gap between the surface of the lid and the fridge although the tub is better sealed now so will have to see how it goes.

View attachment 204395
Sweet looking rig also!
 
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