My search was to insulate a steam boiler. After looking at various hard to acquire foam and foil combination materials that would handle the temperatures, I found polyester batting at the local fabric store in various thicknesses, as well as a inner foil laminated thin version that was used to make hot mitts. This material is good to >300deg F per McMaster and other references, and is VERY inexpensive, albeit a bit fluffy, and had very good insulative properties. There are no toxic particles or debris from it. The first time I used it, there was a little heating smell (some volatiles boiled off), but since works great no odors, etc. Heating duty cycle of the boiler was considerably reduced. I used a combo of the mitt insulation and 1/4" layered material. The lifetime supply (you have to buy it in wide widths) cost about $5 for about 10X as much as needed.
Anyway, it ended up being a very simple solution, and was able to conform to various shapes due to the plumbing irregularities.
Cheers,
Floyd
