Multipanel for Freezer Insulation

[ozmike]

Have ripped out my old and leaking engine driven eutectic system, am building a w600 x d400 x h500mm box using Multipanel a high density polyurethane board 30mm thick, they recomend 90mm base (3 x 30mm MultiPanel), 60mm sides (2 x 30mm MultiPanel) and 30mm topfitting, I am going to give it one more 30mm all round, just to make sure, this will build the box and provide insulation, am going with an Ozefridge eutectic system BD50, twin 500mm x 380mm x 40mm tanks at each end, so far they have been great to deal with, very prompt replies to my e-mails, Ozefridge in conjunction with multipanel set up a fridge using 1 x 30mm sheeted box with the tank inside at the Sanctuary Cove Boat show, here in Australia, it held temp all day after just 1 cycle, John from Multipanel has sent me all the specs (see attached) K & R values, but I don't really understand them, can anybody decifer these, everyone talks about R value per inch/mm.

[daddle]

The problem with urethanes is they slowly absorb water in fridge use and lose their R-value. polyethylenes are the way to go. Usually the blue house insulation board. That said, I built a box out of PU panels. 3 layers of 2 inch boards. Each individual piece was completely sealed in a heavy polyethylene wrapper taped tightly shut against moisture. Worked well in dry-dry Mexico.

[ozmike]

daddle, have asked question about suitability for freezer this was reply:

"MultiPanel has been used in the construction of many custom fridge/freezers.
Most of the fridge/freezers have been the eutectic systems from Ozefridge.
We made a 166 litre cabinet, which holds fridge temperature with ONE run cycle of the Ozefridge system per day. (Once per 24 hrs). The battery consumption is less than 20 amps.To see photos of this fridge unit, please go to http://multipanel.com.au/refrigeration.html
MultiPanel is a closed cell polyurethane composite that is 100% waterproof and has excellent insulation qualities, so is ideal for your application."

[ozmike]

What is the best type of seal to put around lid, am going to make lid in 2 pieces so i can just open one end or the other, will have an 800mm benchtop split in 2, overhanging 20mm on front, with some form of catch on front edge so the lids will be clean of hinges and catches etc, to improve workable bench space.

[daddle]

Originally Posted by ozmike

daddle, have asked question about suitability for freezer this was reply:
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Hmmm. Okay. They must be using some sort of moisture barrier. Polyethylene sheeting of aluminum foil. Or they didn't wait a year in a marine environment before testing.

I made one small mistake in earlier post. I meant Polystyrene foam not Polyethylene. Not STYROFOAM, but Expanded PS Insulation Board. Usually Blue boards at the building stores.

If moisture ingress is a problem. And it's a big one on boats of course. Bare PU is the worst choice. It will be 5% water in a few years. Plus the gas they blow it with, which IS a great insulator, slowly leaks out of the cells and is replaced with moist air. After months or years it will have no useful R-value.

Polyisocyanurate, found at building stores (tan color) is bad too.

Expanded PS foam is hydrophyllic. Water wants nothing to do with it.

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Expanded Polystyrene Vs. Polyurethane Insulation | Cooler Connection | Foodservice Blog Walk-in Refrigerators Coolers Freezers
Rigid Polyurethane Foam

On the lid sealing question: I used Butyl Rubber sticky backed weather stripping. Kinda a heavy dense foam. 2mm thick, 10mm wide. West Marine I think.

Cool tip: I lined my fridge with 6mm foam core PVC board. Used for exhibit displays and the like. Very easy to work with. Ideal surface for durability and cleaning. Sealed it with 5200....which gets a little grimy so there may be something better. Made the whole tapered double sealed lid with it by building it upside down on the workbench: formica, then plywood then foam, then PVC. Then a 2mm temporary spacer. Then built the frame on that. It's beautiful.

Do not put a drain in the fridge. You will destroy the R-value with that tiny hole. Mop or pump the water out.