Worlds largest rocket mass heater

I will post pics as soon as my phone is working again later this week.  10 year follower of RMH stoves, finally living somewhere I can build some.

We have an underground barn in southern Colorado that cannot be salvaged. Elevation of 8400 that cannot be salvaged. 50'L X 24"W X 10"H. The plan is to make it into a RMH. We live on 80 acres and have plenty of mass to fill it in with (boulders to gravel). The previous owners also had a lot of structural insulated panels laying around. We will be putting a decent sized greenhouse above it once filled in. Being that this is a cross between a RHM and geothermal I've considered plumbing it so I can eventually heat up are basement to the house.

I considered building this and posting pics as I go. Upon further thought, I'd rather post this here and get as much feedback as possible.

Would having two rocket stoves be better with this much volume?

Would love all the feedback I can get before I get started. I'm not in a huge hurry so if I get months worth of feedback and research, I'm great with that.

Thanks,

Rodney

So you basically have a 50' x 24' x 10' deep hole? Any structure in/over it now?

If you are planning on it becoming a greenhouse, I would not fill it in completely, but keep at least 5' deep (maybe more) to sink the greenhouse into the earth, sheltering it from winter winds.

Aside from overall greenhouse configuration, I like the idea of a rocket-heated greenhouse. I don't know if you would be able to grow year round, but you sure could extend the season. For that size of space, I think a big RMH would be warranted. A 10" batch box system could support about 80' of half-barrel bell running under beds according to batchrocket.eu, so you might want to have two of those depending on how warm you want to keep the place. One 12" batch box would support more bell length. What is your wood supply like? Even an RMH will take serious fuel to warm a space like that.

It currently has a structure on top of it. I like your idea of not completely filling it in. It's mostly wooded here so wood supply shouldn't be a problem. Right now I lean towards plumbing it for two stoves. Test it for a while with one and if that can't keep up, I'll add a second.