Jeff : A late Welcome to Permies.com -You are thinking outside the box

(your greenhouse-literally

) !
Can i suggest another look ! With Your
Rocket Mass Heater RMH in the green house you automatically have brand new heated raised beds!
Don't be afraid to make them tall, your back will thank you!
Your vertical chimney should only give you problems if it is too short, always locate your vertical chimney on the lee side of the structure,
these are the two most common things to forget and make trouble for yourself !
There is an entire Forum
Thread on Rocket Mass Heaters in Greenhouses, near the top right of this page is the Permies Toolbox, here you
can find and click on the
Search Link, enter a specific topic "Rocket Mass Heaters in greenhouses'' then select all forums and check
to make sure you are doing a google search within Permies !
Also in the Toolbox is the
my profile link please click on this and update you information next to your name ! Who knows, you may
find a Permies member with RMH
experience w/ greenhouses is a near neighbor ! hope this is timely and helps !
Think like Fire! flow Like a Gas! Don't be the Marshmallow! As always your questions, and comments are solicited and welcome Big AL