The more I look at all this, and after reflecting on some more recent threads, I think Hot Rod hit the nail on the head (no surprise!) with his suggestion of a Laing 12vdc circulator + maintenance charged 12vdc battery.
The Laing pump is not cheap by itself, but it allows one to omit a lot else (automag valve and lots of tanks and plumbing)- which ends up cheap enough when you look at it from the big picture/ long run/ reliability perspectives.
The 12vdc battery is normally kept charged when the "grid" is on. When power goes down, a relay that's normally energized by the grid "drops" and then, as it does so, connects battery power to the Laing 12VDC circulator, which pushes water from the wood gasifier round and round through a [whatever is chosen] simple dump load (in my case, it'll most likely be a loop of ox-barrier pex at the basement ceiling/ under the floor). Include a check valve if your layout gives concern about inadvertent flows.
No worries about achieving gravity flow or how long it takes for the boiler to achieve a soft landing.
WAY simpler to build/ control and WAY more cost effective than UPS-es, tanks, and whatever. Only thing left to confirm, if someone can, is whether the Laing circulators are OK sitting almost always dormant for who knows how long, only to be energized if the power goes out. I recall reading that some of the "regular" wet rotor circs may seize up if left dormant and not "exercised" for a long, long time. I'll try to check with Laing, and also have my hands pretty full with the day job and the arrival of my Econoburn tomorrow.
The Laing pump is not cheap by itself, but it allows one to omit a lot else (automag valve and lots of tanks and plumbing)- which ends up cheap enough when you look at it from the big picture/ long run/ reliability perspectives.
The 12vdc battery is normally kept charged when the "grid" is on. When power goes down, a relay that's normally energized by the grid "drops" and then, as it does so, connects battery power to the Laing 12VDC circulator, which pushes water from the wood gasifier round and round through a [whatever is chosen] simple dump load (in my case, it'll most likely be a loop of ox-barrier pex at the basement ceiling/ under the floor). Include a check valve if your layout gives concern about inadvertent flows.
No worries about achieving gravity flow or how long it takes for the boiler to achieve a soft landing.
WAY simpler to build/ control and WAY more cost effective than UPS-es, tanks, and whatever. Only thing left to confirm, if someone can, is whether the Laing circulators are OK sitting almost always dormant for who knows how long, only to be energized if the power goes out. I recall reading that some of the "regular" wet rotor circs may seize up if left dormant and not "exercised" for a long, long time. I'll try to check with Laing, and also have my hands pretty full with the day job and the arrival of my Econoburn tomorrow.
