Rocket Mass Heater in an inground Walipini

I'm looking at building a Walipini glass house to extend my growing season. (Frosts can occur as late as November and as early as mid-February playing havoc with some tender growers!)

My land is flat, so the Walipini will be substantially below ground level. (Excavations will build up surrounding land area).

I am also considering a Rocket Mass Heater also into the build.

My question is regarding the flue of the RMH. As it is cold gas that is being vented, it will not rise. So I'm after suggestions and guidance on how I am best to flue the RMH as being below ground level external venting is not possible.

I'm still in the planning stage so it's my chance to get the best plan before I start building.

Thanks.

Hi Scott.

In a walipini You can perfectly use a rocket mass heater. A well designed one, should never have an axhaust temperature of less than 60C°, so against any condition on earth, that rises. There's very few, who have managed to have good results with an horizontal flue anyway. So have a chimney. May be a clever way, would be to have the flue path in a U shape, with the chimney next to the barrel. And even better, having a bypass gate, for startups, which can be anoying with a cold mass.

Myself, i'm a partisan of batchbox rockets, and bells. But even with a J tube and bench mass, you can have success in your walipini