Ice Box Conversion to Spill Over Fridge/Freezer

[SV THIRD DAY]

Looks great Stephen.
It's definitely a project that isn't "Rocket Science" but it is WORK.
Keep it up with the great photos so we can point people to this thread for encouragement that there is life after a boat Reefer Box rebuild!

[Typhoon]

75 minutes in , looks like polyiso is loosing to XPS or blue board. I will repeat this test . But I am convinced that polyiso suffers at low temps . Graphs to come .

Regards John

[SV THIRD DAY]

but how thick is your test plug.......If it's not the typical thickness of a Box wall you only have one piece of the data and can make the wrong conclusions....been there....seen that before.

[Typhoon]

One inch thickness . I didn't have all night , they were neck and neck until 9c then the then polyiso started to give it up . Still going to do a warm up test and another cool down , this is just preliminary . Did you ever do any tests Rich ?

Regards John

[SV THIRD DAY]

Originally Posted by ColdEh Marine

Did you ever do any tests Rich ?

Yep...two 7CF Test Boxes each set up with 4" of PolyIso vs 4" of Blue Board.
Published the data a few years ago...being around since 1968 has it's advantages....

[Typhoon]

This may inspire me to do another test with a full 6 inch block . Just to confirm my findings .

Regards john

[SV THIRD DAY]

I never did a 6" poly vs blue test...so more data to the party will be a great thing, but the challenge as always is....will people believe it...ha ha ha.

Cheers

[Typhoon]

Always the challenge partner .

My freezer is not big enough for both blocks so I will have to track them separately . I will start to build them this weekend .

I just want to make sure my data is correct , so far what I have , confirms all the tests I have read .

Regards John

[malbert73]

Originally Posted by SV THIRD DAY

Yep...two 7CF Test Boxes each set up with 4" of PolyIso vs 4" of Blue Board.
Published the data a few years ago...being around since 1968 has it's advantages....

What are results? Any link to pub?


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[SV THIRD DAY]

Add a third test block:
1: outer inch of Blue which will see the coldest temp with the rest of the core inches being poly iso for the added R-valve.

That's the best configuration I've found.

[boatpoker]

Originally Posted by funjohnson

Looks awesome.... but doesn't having the doors side made of highly conductive aluminum defeat a lot of the benefit? It looks like the heat would find an easy access point into the freezer.

Matt

There is a very small amount of transfer but because of the way the gasketing is done, none of the aluminum is directly exposed to the interior. I'll be keeping an IR gun handy over the next few days and see if I have to modify the gasketing method but at least it is air tight.

[john61ct]

So that's for when we're trying to keep the heat inside?

For a fridge box, keeping the heat out, make the 1" of XPS innermost, balance to the outside being polyiso?

[SV THIRD DAY]

Originally Posted by john61ct

So that's for when we're trying to keep the heat inside?

For a fridge box, keeping the heat out, make the 1" of XPS innermost, balance to the outside being polyiso?

Correct, but for John's test where the test cube is being put inside a cold box, we would want the blue board on the outside to be exposed to the colder temps.

The best configuration I found in our 7CF Box testing is 1" of blue board on the interior wall followed by 3" of PolyIso.

[john61ct]

Well that must assume a 4" total right? thicker polyiso would add some incremental increase in R-value

[SV THIRD DAY]

Originally Posted by john61ct

Well that must assume a 4" total right? thicker polyiso would add some incremental increase in R-value

True...
4" is the ideal but boats are not ideal, so you live with what you can do.
I just helped build a box where 3" was all they could do so they did 1" of blue board followed by 2" of poly iso.

a good rule of thumb is that for every doubling of the insulation, you cut your daily power usage about in half! So turning 2" into 4" may sound trivial but it's a big deal at the end of your Amp Hour day.