This is from Kollman's site (http://www.kollmann-marine.com/insulation.html
Keep moisture OUT!
The worse thing that can happen to an insulated box is to have moisture penetrate into the layers of insulation which renders it useless as moisture is one of the best conductors of heat. A good insulation system for any refrigerator/freezer would be insulation that is encapsulated in plastic. If you cut open a new commercial refrigerator
, you will find that all the insulation is covered with blankets of plastic that prevents any air from moving into the insulation. Air in the humid climates will deposit its moisture on any surface that is 10 degrees cooler than the ambient air. This means that a refrigerator operating over a long period of time with air leaks
into the insulation will continue to accumulate moisture until the insulation reaches its saturation point. It is true that the new closed cell foams resist the moisture but there is still a loss in the "R" value over a long period of time. Therefore, if you are building a new box, make sure that the insulation is cocooned in a plastic of 4-6 mil. similar to that, which is primarily sold for paint
drop cloths. This can be purchased at any hardware
store. There should also be one reflective layer of aluminum
foil somewhere in the insulation with the shiny side toward the sun. This can also be found in your home refrigerator. If you are building your own box, the standard Reynolds wrap Aluminum
foil will work.
Currently, the inner box and door are attached to a 4 x 8 panel that is party of the galley's wood work. I am not going to replace that. This panel has a frame in the existing opening to allow me to mount the whole assembly as a unit.
I building an outer layer of fiberglass to protect the insulation from damage when this assembly is removed and reinstalled.
Reverse reflective layer. Put it next to hull!
No intentional ventilation in the outer layer. But, there are opening for temperature probes and coolant
lines for plates.
I am putting the fiberglass batting in bacause the alternative is to put nothing there. The space next to the hull
has stringers, conduits for plumbing
, conduit for wiring
bracing materials for cabinets, opening for propane
line, curved surface for hull, etc. The refrigerator box is rather regular. Already I have to cut the foam somewhat to get around a hull stringer. The fiberglass is the maximum amount I can get into this space. It also allows me to maxmize the insulation where I have space and shrug when there is no space. Kollman says to try to get to R30. I can't get 6" of foam necessary for R30 all around the box. I can only do 4" for about 95% of the box. The combination is an attempt to get to R30.
Thanks for all the help!! Helps to have additional eyes!