Hi folks! We lived with this lovely heater for 4 years and can personally recommend the design!
To purchase the plans, please click your choice of payment below.
Once you have made your purchase with pie or Paypal, you will find a link at the bottom of this post. Click to download, and that's it!
This project also has been featured in a lot of free, online articles:
The fun we had working our way through the permitting process in Portland, Oregon, article on our website HERE
Free video that includes process photos from building this heater (one hour video presentation, we show the Annex 6" building process from 40:00 to the end).
If you already got these plans from us, and have built a rocket mass heater using these plans, we'd love to see your photos and project stories here too!
Annex 6" Heater Plans
An L-shaped heated bench, using the rocket mass heater clean-burning and super-efficient wood burning technology. The '6' refers to diameter of heat-exchange ducting.
This design provided the sole heat for an older Portland cottage/apartment of about 800 sf. Over 4 years, we used less than half a cord of salvaged wood per year (local arbor trimmings and building debris). We ran the fire 2 to 4 hours in ordinary cool, rainy weather, and up to 6-8 hours when the weather dropped below 20 F, for constant 24-hour warmth. In summer, the earthen bench was not heated, and instead helped keep the house cooler than it had been in previous years with no need for fans.
The document prints letter format 8.5" by 11, or 11" by 17", six pages including photos; scale drawings of the floor plan, elevation, and sections; a cutaway view; and builder's notes on the construction process.
These are as-built drawings for information only; no guarantees or licenses implied. References to ASTM standards and building codes are included to help prospective builders research local building requirements.
I just found an older thread showing some early drafts of diagrams from these plans, HERE.
This diagram shows the "snapshot" version, which we used to illustrate the stove for our Portland permitting efforts. We also used this diagram as the base for several illustrations in the first chapters of our Builder's Guide.
The full plans include a finished version of this diagram, and several more blueprint-style drawings for top view, side views, and details.
This was the first heater project Ernie and I built in our own home, just after we got married, so it has some good memories for sure!
We only slept on it ourselves for a few days, during an extreme cold snap, but we had a lot of happy, cozy guests that "couch-surfed" during those 4 years.
(Not all of the guests who slept on it had intended to spend the night. We had one particular pair of friends with stressful jobs who would come over for dinner, we'd sit down for a drink and conversation afterwards, and he would just melt on the bench and fall asleep on her shoulder.)
Ernie and Erica,
Thank you both so much for providing this material to the BWB backers. You're generosity and willingness to help spread the word about this technology is very much appreciated.
Have a great day!
From a chilly South African high veld, thank you for the fantastic work you are all doing. While my own garden in a residential complex is tiny, so much information can be adapted, and providing efficient heat is marvelous. Many kind regards.
Thanks for this great resource! We will be building our first RMH this year and are hoping for a similar design, though we'll have a U-shape instead of L-shape.
One question on exhaust pipe length: Would it be feasible to have the exhaust pipe run through the RMH only once (instead of back & forth as in this design), and then exit vertically through our roof? Is there a length of exhaust pipe limitation due to heat/speed of the exhaust? We have a loft above the RMH and are wondering if we should design the pipe to pass through the loft to use that heat... or if there won't be any heat left by the time it travels through the RMH and then up 8' of pipe.