[Ant]

Maurice,

Sounds like good memories, we had the big woollen mills next door to my parents beekeeping business and I spent many an hour roaming the lagged pipework etc, that work is now all long gone overseas for cheap labour and we and the mill are no longer there!

What I have used is KA Wool (white dense cotton wool like) I think it is used for boiler lagging as it can sit against a boiler and not burn or transfer heat, but doesnt like water so its very good behind slight stand off firewalls probably more so if you have under floor exhausts if you used thin alloy panels and sandwiched the wool if heat is an issue!