Thermal conductivity numbers for boat fridge construction

[GILow]

Originally Posted by LouK

Please note that closed cell polyiso is non-hygropobic, does not absorb water & this is why it is used in roofing all over America. It’s also the reason why ‘blueboard’ Or other open cell foams are not used in roofing systems- as they do absorb water & thus would blister the membrane during the summer.

In compact assemblies or membranes like a roof or your ice box, polyiso is hard to beat.

Thanks Lou, that's interesting stuff.

One of the threads linked by john61ct has some discussion of polyiso, I can't remember the conclusion, but ColdEh was investigating and discussing the merits of polyiso over time, and I seem to remember there was some minor issue about it losing a small portion of its insulation effectiveness.

I will go back and have another look when I can.

[john61ct]

Nothing lasts forever, all foams have a lifespan, then need to be replaced.

No one expected plastic boats to last either

[LouK]

It’s true that all insulation loose their resistivity over time & this is why generally when we design w/ polyiso we use ‘aged’ or long term values. I suspect that it will age much more slowly when nestled between your hull & ice box than in a roof where temps can easily get up to 160-180 deg.

Trust me, if there was anything better & more affordable, we’d be using it in our buildings.

Lou K, AIA, LEED, EDGE Energy Expert

[newhaul]

Originally Posted by john61ct

The keys are **per thickness** as well as availability & cost.

R-values are not constant across all temperature ranges, so stats from home construction will vary from refrigeration use cases.

Tests have shown the most effective bulk insulation at reasonable price for freezer / fridges is polyiso.

But with a 1/2" of XPS, aka Dow styrofoam/blue board, as an inside layer to buffer the polyiso from the most extreme cold temps.

the best I have found ( and what I am using) pacor foil lined Cryogel Z.
R8.7 PER 10MM or R43 with an approx 2 inches thickness.
Cryogel® Z – Pacor, Inc.
Not the cheapest but if you have limited space its the best.
And the colder it gets the better it works.

Also IMO a good idea to get some for the lid. If nothing else.

[john61ct]

Yes similar to Aerogel, but wow pricey

[newhaul]

Originally Posted by john61ct

Yes similar to Aerogel, but wow pricey

it does seem that way till you take into account the width of that roll is 4 inches shy of 6 feet. So the 15 ft roll has over 70 sq ft which while expensive its only 7 bucks and change per sq ft.

Boats ain't cheap.

[GILow]

Originally Posted by newhaul

Boats ain't cheap.

NOW I learn this..!?

[ayates]

Unless, there key functional requirements such has minimal space, my feeling is that extruded styrofoam is the most cost effective and long term solution. I suspect that any small variance in R value between foam types will be minimal compared to other leaks and such.


Allan.