TomP10 wrote:Good question --- no one was able to give a good answer on the HB forum either.
The subject seems to be something like the 1,000-pound gorilla sitting on home plate; everyone's pretending it isn't there.
I've had a couple of espresso machines with an insulated boiler. One was a Quickmill chrome box with some sort of plasticy or rubbery "stuff" wrapped around the boiler. By the time it was about a year old, the insulation disintegrated into a fine powder when touched. I sent it over to Chris' Coffee for some repair, and they stripped it out and returned the machine uninsulated. So whatever that green "stuff" is, don't go there. :)
Then I had a Cimbali Jr with a factory-insulated boiler. It appeared to be foil-backed fiberglass, was quite effective, and lasts pretty much forever. It can be a tad messy to work with in large quantities (like truckloads), but for small pieces like we would use to insulate a boiler, it shouldn't be an issue. A small piece would easily wrap right around the Vivaldi steam boiler. But any foil backing should obviously be kept away from electrical connections.
However -- and I haven't explored this; I'm speculating -- I'm not sure I would want to insulate the steam boiler. Yes, I would want to reduce heat and electric consumption. But the boiler is regulated by temperature, not pressure, and very rapid heat loss upon reduction of pressure is necessary to maintain a narrow delta. I wonder whether, at least in theory, insulating the boiler would slow the heat loss enough to increase the delta, thereby making it less responsive to maintaining adequate pressure. If the boiler were on a pressurestat (like the HX machines I just named), that wouldn't be an issue, but the designers chose a different path.