Rebuilding Fridge / Freezer - Materials ? From Where ?

[CharlieCobra]

I'm getting ready to redo Oh Joy's galley and one of the projects is to build new fridge and freezer boxes. Has anyone on here done these? What did ya use and where did ya get it?

[pressuredrop]

charlie, i am doing the same thing as you, i just purchased 4 sheets of the dow 1'' blueboard (r = 5), i might need one to two more, but i plant to cut all the sheets, glue them together, glass the outside, and using a male mold make a fiberglass liner for the inside. they say, you want 4" of insulation for a fridge and 6'' for the freezer, good luck and keep us posted

[captain58sailin]

I too am planning on building a top loading refrigerator on Rose, and I will be interested to see other's ideas. I was thinking about using the 2 part pour foam and building a form for it, I have yet to hear back from the foam people as to the R factor for their different density foams, if I do, I will be sure to post the numbers here. Also where does one acquired the cooling plates needed?

[CharlieCobra]

Isotherm makes systems for hand built boxes.

[mesquaukee]

The best insulation is polyurethane sheet with aluminium foil on its’ face followed by expanded polystyrene and then foamed in place polyurethane.
I would not reccomend poured in place foam. The manufacterers R factor is for foam made in a carefully controlled enviroment. Temperature, mixing and any restrictions to expansion will greatly reduce the R value. The size of the gas pockets and wall thickness influence the conductivity of heat.
The insulation values are,
Material R-value (1/BTU/hr/sqft/Fº)
Polyurethane sheet 7.0
Polystyrene (blue board) 5.0
Poured polyurethane 4.5-6.0
Styrofoam 2.0-3.0

The higher the R-value the better is the insulation.

I have ripped out a number of boxes and have always found large air pockets and very dense areas of foam.
The best boxes are made of foil covered polyurethane foam readily available throughout the US. The thicker the insulation, if you have the space, the less the AHr/day. I have a 9 cuft fridge (6') and a 4 cuft freezer (8') and use a paltry 55 Ahr/day in the tropics.
What is critical and usually overlooked is a vapour barrier around the outside of the box if you plan to use it in the tropics for extended periods of time. A painted or urathaned plywood shell is not sufficient, it allows moisture through it. Over a period of time moisture will build up around the liner incresing the heat flow and it also causes other problems
Polyethelene plastic works well. Use several layers of 6 mil plasic and seal all the seams.
I would reccomend building the cabinet which would contain the box first. Line it with a few layers of polyetelene then build up layers of poyurethane foam. Cut fiberglass sheets to fit the interior, gluing it to the foam and then bond the panels together with caulking or by fiberglassing the seams. Don't forget a drain!
This may sound a bit crazy but you want the liner to leak a little. This is to allow any moisture that gets past the vapour barrier to be drawn through the liner to the evaporator plate.

If you are planning to use a 12 volt system do not purchase a cold holdover plate system. They are power hogs. You will be using 1-1/2 to 3 times the AHr/day to cool the box.

.

[Badsanta]

check out r-parts and this guy KollmannMarine Boat Refrigeration Specialist no connection other than as a customer.

[bhenry]

I went through this last year and went with blue board and Seafrost equipment. Cleave, the owner will help you design the system and is great to work with. Just a happy customer.

Impressive work on the boat. Seattle weather has been good to you.

Bill

[slacker]

http://www.cruisersforum.com/forums/...box-26977.html

[svtrio]

I removed poured-in foam from two sealed flotation compartments. Twice. Over a period of several years they became thoroughly waterlogged.

I had polyurethane sheets that were rained on, which became watersoaked, but not the blueboard, and that became my choice for rebuilding my cooling boxes.

Roger

[mesquaukee]

It might not seem like it but water is slowly absorbed by all and every type of foam, blue board, pink board, poured in place polyurethane, sheet polyurethane, polyisocyanurate foam, etc.
It is slow and insidious. It is driven by vapour pressure. If you have taken a scuba course it is the same as the problem with nitrogen, exactly the same mechanism.
A vapour barrier or more correctly a “vapour retarding barrier” is essential. Without one over time your compressor will run more and more often.
I have attached some files which show the rates of water absorption using various enclosures.

There are a lot of misconceptions about what an efficient refrigeration system is.
It’s all about the lack of knowledge. It is easy to know if you approach it by using thermodynamics. A theoretical system can be easily designed, it’s simple. Then theory is turned into reality which involves a lot of soldering.
In Cruising World back in March of 2006 an article by Douglas Bernon called "Cruising on Ice", Log of Itaka, describes the design and construction of such a refrigeration system in the San Blass. It was made with parts readily obtainable in Latin America.
I have a lot of info on how to construct a system that I am willing to share with anyone who wants it. I would like to post it all here but there isn’t enough space.
Drop me a line if you want it.

[CharlieCobra]

You can PM me with it if ya like.