Insulating Foam

[jpjamo]

Hi Materials Gurus,

I am looking for an insulating foam for a hot water boiler application. We have used polystyrene but it is borderline for the temperature requirement.
1. Needs to be ok for continuous use temp of 100degC - or slightly higher.
2. Needs to be moldable with a less "environmentally damaging" blowing agent such as Pentane (or any other you suggest!).
3. Final molded thickness will be 25mm.
4. Want as low thermal conductivity as possible
5. Should be able to handle the possibilty of exposure to moisture.
6. Want to stay away from Polyurethane due to its lack of recycability.
7. Flame retardency required to meet appliance standards
8. Oh and needs to be as cheap as possible!

Any other info I have left out?
Ones I have looked at briefly are BASF Basotect and Sabic (GE's) Noryl EF. Basotect is some melamine formation which not knowing much seems like something to avoid from an 'eco' point of view?
Polypropelene has been suggested but has the negatives of requireing pre-expanding (before molding) so you are shipping a lot of air doubly and is less stable post molding??

Any suggestions, thoughts, corrections to my current understanding is greatly appreciated.

Thanks
James

 

[Compositepro]

Most water heaters appear to use polyisocyanurate foam insulation.