Torpedo Propane gas heater

So I have this weird idea. I have dug out a mount of dirt in my greenhouse and will be putting a pipe under the mount of dirt. Instead of using a rocket mass heater because the pipe is too long to draw draft, can I use a torpedo propane gas heater to blow it in?! Is there anything that can hinder it?

Sure you could. But I doubt you would gain much in terms of efficiency. To my mind it would be a long exhaust pipe rather than an engineered system designed to capture and radiate heat. My 2c.

why?

What if you had the pipe go along and then all the way pack, where the exhaust was next to the heat source, and the air in the exhaust slightly heated? That would create a draft for you, I think, and you could probably do that for a rocket mass heater.