# Urethane foam for refrigeration?



## SanDiegoChip (Jun 12, 2007)

We are preparing to add insulation to the inside of our ice box. Then we will be building a refer unite to keep it cold. 
In the book “Refrigeration for Pleasure Boats” by Nigel Calder on pg 11 he states “Urethane foam is the only kind of foam that should be used in an icebox construction.
I have searched the web and seem to find lots of different kinds of Urethane foam. It is not a simple task to find the correct foam. We have some closed cell foam from Home Depot we use for knee pads but am assuming this is not the correct type either.
Where can I find this Urethane foam Nigel is talking about?
Thank you,
Chip


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## downeast450 (Jan 16, 2008)

Chip,

Nice boat! Nice web site, too! Here is the foam. Urethane Foam , Expanding Marine Polyurethane Foam

I have used it several times. Pour when conditions are above 80 degrees. It has huge mess potential. Stir vigorously until it begins to fill and almost overflow the disposable cup you are using to mix it in(I use 1 quart paper pots, 2 to measure the two parts to mix and one where I combine them to stir. This way I can use the measuring cups over and over. One batch per mixing cup.). .Continue to mix as you pour. It expands to about 25 times volume of liquid. Small batches will work. I use about 3 oz. of each part mixed together for each pour. Wait 15 minutes between successive pours. Leave the top of the space you are filling open so excess can foam out. It can exert some pressure and will distort its container if it is confined. The hardened foam can be cut and sanded easily so removing excess is an easy job after it cures. It is hard to remove from anything if you spill it so mask and cover everything with plastic that you don't want foam on. Wear disposable gloves too, or you will wearing foam until it wears off. Have the space you are working in well ventilated. I keep a quart of acetone and a roll of paper towels handy for emergencies. It helps with immediate clean up but won't get everything off anything and may take a finish off in the process.

Good luck,

Down


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## bb32 (Jun 14, 2006)

If your surfaces are flat enough this might work, might be a couple percent less efficient but sounds a whole lot easier:

"Rather than using "Blue Board" which is Dow's trademark for expanded polystyrene, check out polyisocyanurate insulation board. Dow's stuff has an R value of about 4 per inch. polyi has an R value of about 7-8 per inch, almost double the insulation value.
Polyi can be purchased at Lowes and Home Depot. It is yellow or orangeish color and is often foil backed."


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## SanDiegoChip (Jun 12, 2007)

It will be hard for us to have a 80 degree day here at the dock in San Diego. Could be at the height of summer. Could I guess try to heat up the boat. Also I would rather work with sheets of foam. Say ½ inch sheets. I am trying to find urethane sheets of foam. I guess I should have been more specific. 
On the other hand I guess I could put a piece of say fiberglass on the side of the refer and then poor the foam into the space creating a layer. There are problems to this method as there is a lip for a shelf I want to preserve. It may work fine for adding to the bottom though. At any rate still sheets would work fine also.

I keep getting Polyurethane products.
Here is what I have found and am thinking even Home Depot may have what I am looking for. Problem is there is no one to ask that seems knowledgeable on the subject there.

Thanks for the compliment!

I have called a few lumber yards and manufactures and have yet to find the product.


“Polyurethane Insulation Materials
Polyurethane is a closed-cell foam insulation material that contains a low-conductivity gas (usually hydrochlorofluorocarbons or HCFC) in its cells. The high thermal resistance of the gas gives polyurethane insulation materials an R-value typically around R-7 to R-8 per inch.
Over time, the R-value of polyurethane insulation can drop as some of the low-conductivity gas escapes and air replaces it. This phenomenon is known as thermal drift. Experimental data indicates that most thermal drift occurs within the first two years after the insulation material is manufactured. The R-value then slowly decreases. For example, if the insulation has an initial R-value of R-9 per inch, it will probably eventually drop to R-7 per inch. The R-value then remains unchanged unless the foam is damaged.
Polyurethane insulation is available as a liquid sprayed foam and rigid foam board. It can also be made into laminated insulation panels with a variety of facings.”


“Polyurethane products are often called "urethanes". They should not be confused with the specific substance urethane, also known as ethyl carbamate. Polyurethanes are neither produced from ethyl carbamate, nor do they contain it.”

“It is important to note that urethane foam is most commonly used to refer to a material made from polyurethane. The urethane reference in this name is to the type of links, also known as carbamates, which join the units in polyurethane. There is some potential for confusion as the word urethane on its own is often used for a specific carbamate also titled ethyl carbamate. Despite the name, this substance does not appear in urethane foam.”

“Urethane foam can also be used for insulation. The biggest advantage of the substance for this use is that it has a very low lambda value, which is the measure of how much heat it transfers, meaning it is a very effective thermal insulator.”

“Strong and resilient, polyethylene foam is often sold as closed cell foam sheets. It is used as thermal insulation, as shock absorption, to dampen sound, and as cushioning. It is very buoyant and is frequently found in flotation devices and other nautical equipment.
Polystyrene, also called Styrofoam™, is a lightweight foam that is easy to work with. It is used in construction as insulation because of its almost complete resistance to moisture, water vapor, and mold. It is also a popular choice for arts and crafts and packing material.”


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## SanDiegoChip (Jun 12, 2007)

*Polyi*



bb32 said:


> If your surfaces are flat enough this might work, might be a couple percent less efficient but sounds a whole lot easier:
> 
> "Rather than using "Blue Board" which is Dow's trademark for expanded polystyrene, check out polyisocyanurate insulation board. Dow's stuff has an R value of about 4 per inch. polyi has an R value of about 7-8 per inch, almost double the insulation value.
> Polyi can be purchased at Lowes and Home Depot. It is yellow or orangeish color and is often foil backed."


 As I posted I saw your post, how funny.
Thats what i was hoping for. 
The Polyi at Lowes and Home Depot. 
Thanks,
Chip


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## SanDiegoChip (Jun 12, 2007)

*Polyi*



bb32 said:


> Polyi can be purchased at Lowes and Home Depot. It is yellow or orangeish color and is often foil backed."


Do you know if it is mold and water resistant? Like closed cell foam?
Thanks,
Chip


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## SanDiegoChip (Jun 12, 2007)

*Home Depot foam*

This is a boat like ours. This person has tore out the old box and created a new one. We would not want to do this. It does show that he used Home Depot foam.

"This pic shows the old fiberglass box lined with layers of closed cell, foil covered foam sheets (Home Depot). There are 7 inches on the bottom and 4 inches on each side, with spray- in foam in the irregular cavity on port side. The ply panel on far right is to provide a suitable mounting surface for evaporator screws. Next step was to cut a 3/4" ply cover for box, fitting it flush with the original box lip."


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## SanDiegoChip (Jun 12, 2007)

*The refer*

I went to Lowes yesterday and looked at the yellow insulation in sheets. I think it was a R-5. They were I think ¾ sheets.
So we know how to do it just not the best foam. I am guessing I will go with the yellow sheets.
This is a boat just like ours. This is the refer. Next to it is the freezer. It is an overflow system. About 7 cft.
This does not show the freezer part.
First it was coated with fiberglass I think. I have not found the "how we did it" yet.
You can see how he filled the first section of the bottom.
Then they added foam. 
Then fibreglasses it.
The bottom is way too deep and it can be filled up about 4 to 6 inches. 
The outside of the box has little room for adding insulation.
Some sides can get 3 inches.
Some because of entry limitations can only get 2 inches I think.









































He preserved the shelving platforms.
Again this looks like the white Home Depot stuff.
I am still looking for his how he did it text.


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## ulferlingsson (Jun 10, 2010)

McMaster has a lot of stuff, and you may find some useful info too. See Thermal Insulation, McMaster-Carr


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## deniseO30 (Nov 27, 2006)

Just a suggestion to anyone making or attempting to super insulate the box or boxes .. don't forget the lid! Make sure the lid has a inch or so of insulation and it's gasket is tight! Moisture and air intrusion = frost and longer running cycles.


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## SanDiegoChip (Jun 12, 2007)

Here is what one boat mate has done and another boat neighbor used home depot foil backed foam. But is it really R20+?

I used a foil covered R 20+ that comes in 1,2 inches thick 4x8 sheets and I bought it at home depot. that was a couple of years ago and I don't know there might be something better out there. It was very easy to use and yes I have been happy with it. It might have been the only thing available that was moisture resistant. Doesn't sweat. 

I have been looking around McMaster Also.
Chip


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## sailingdog (Mar 19, 2006)

I wouldn't recommend using a Polyisocyanate foam on a boat. The stuff makes toxic smoke if it ever catches fire, and on a boat, there's no where to hide from the poisonous smoke. * The ISOCYANATE means that it will produce cyanide based toxins if it ever burns.... not what you want on a boat. *

Make sure what ever insulation you use is completely sealed and will not have condensation or moisture intrusion. Any moisture or condensation will ruin its insulating rating pretty quickly.

Also, listen to Denise's advice, as IIRC, her day job is refrigeration.


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