Could I retrofit a stratification chamber to this and still have draw?

Title says it all and I have pictures to further explain. I messed up and am no longer in budget, our greenhouse is built off the side of the house and we're having to leave the windows open and run the fume hood into there to keep it above 50 degrees because the heater is just not cutting it. I have to load wood constantly and the alker that I mudded it with barely gets hot. I thought maybe burying the pipe literally 6" underground is a bad idea so maybe a strat chamber with a mass will help?

Hey Dom;
With your build, a strat chamber will gain you more heat.
You were warming the ground with a buried pipe.

How long is your burn tunnel?
With a 5" J-Tube it is no wonder you are struggling to warm things up, they only burn for 30 minutes or less.
We normally suggest that a 6" J-Tube is the smallest one to build.
Having lived with J-Tubes, I recommend that an 8" is the only size worth building.

Any chance you can increase the size while adding a strat chamber?
Also, your drawing does not indicate whether you are replacing the underground pipe or hoping to have both a pipe and a strat.
You can not have both.

Forgot to add, greenhouse is small (under 200sqft), polycarbonate windows and roof, walls are solid wood, insulated, double layered, and 5ft tall.

I was hoping adding the strat chamber to the tube below ground would work. .... that's not good news. Dang.

To answer the question the exhaust tube is about 12ft horizontal before exiting.

Hey Dom;
I really think it won't work like that, but it looks easy enough if you want to try.

I was not asking about the pipe through the mass.
I wanted to know about the burn tunnel between the feed tube and the riser.
You can measure wall to wall for an overall measurement or just measure the roof from the feed tube to the riser.
It is very easy to make this spot too long.  10" is an ideal roof measurement.

Does the greenhouse have any insulation underground around the perimeter, so that you are not conducting the mass heat to the outside?