A lot has been posted about boiler insulation over the years. Interest has waned a bit, possibly because many modern machines are insulated at the factory. But those of us who have older machines with substantial sized boilers still deal with this issue.

Our brethren over at Kaffee-Netz have discussed an insulating material that has had little or no attention on HB as far as I can tell - wool. It has a high kindling temperature (up to 500 C supposedly), it is pliable, has a very high R value, and is non-toxic. A few people on Kaffee-Netz have reported using it to replace asbestos in creminas and commercial machines with no problems after a year or more of service.

Jim

Seems the guys at Kaffee-Netz have been using 10cm, but I have seen a picture of 2 group Bosco with insulation that looks like 2-3 thinner layers.

https://www.kaffee-netz.de/threads/kess ... lz.106252/

Easily available in Germany but I don't know anything about US availability.

Jim

Wool felt is now standard for insulating carpets and ceiling panels. A quick search shows it comes in ratings F5, F7, etc. Not sure what the ratings mean. Since it's used where asbestos rolls were once used; it probably is a safe substitute for all former asbestos uses, including boiler insulation.

How would wool compare to a ceramic fiber blanket? I have a 12"x24"x1/2" piece and was thinking of insulating my boiler with it. I was also looking at aerogel but that looks too difficult to work with.

Correction to my post above. I meant 10mm thickness.

Jim

This site suggests an R value of 3.5-3.8 per inch thickness. I believe that compares favorably to most synthetic blankets.

https://myecohub.com/sheeps-wool-insula ... -and-cons/

Jim