[Greenbuilding] foam in a can

[Reuben Deumling]

For purposes of filling gaps in the insulation of a new water heater I'd
like to use a foam that exhibits a high R-value per inch when cured. This is
a rather small volume we're talking about. Can I use pretty much any product
or are there pros and cons relevant to this application?

I own a foam gun for the Great Stuff Pro cans, but I'm not sure that product
line is well-suited to this purpose.

One of these days I also hope to re-insulate an old refrigerator with
something similar. The walls on it are all roughly 3" thick, and I expect
I'll want to send the foam in with as long a nozzle as I could get. Perhaps
this is a different or not even feasible project. Total volume for this
project would be about 8 cu ft.

All thoughts welcome.

Reuben Deumling