I know of someone who made a custom evaporator for their woodstove. I don't see why one couldn't be made to fit on top of a rocket mass heater barrel. It probably wouldn't be quite as efficient as a rocket stove, but then you're also using the heat for multiple purposes. And if you're not talking about massive amounts and don't care if it takes longer then I'd say go ahead and try it.
Creator of Shire Silver, a precious metals based currency. I work on a permaculture farm. Old nerd. Father.
Location: Upstate NY, zone 5
posted 2 years ago
The scale of production is the critical factor here. If you want to make some maple syrup for your family, a pan on top of the RMH barrel might work. Whether you will want to run your RMH for the time needed to evaporate is another question. (A rule of thumb is 1 gallon per hour per square foot of pan surface.) Humidity from 5 or 10 gallons of water being evaporated inside your house in a day might be an issue.
If you want to do any scale of commercial production, you need an outdoor evaporator, not an RMH.
I experimented a little last year with a rocket stove evaporator setup. It was thrown together last minute I hope to improve with a bit more permanent of a set up this year. The thread can be read here. It was not a rocket mass set-up just rocket stove...