posted 1 year ago
Hi Peter; Welcome to Permies!
Also congratulations on becoming an apprentice rocket scientist!
After you have successfully built your first working batch box you will become a true Rocket Scientist!
Your certificate, lab coat, and pocket protector will arrive as soon as supplies are back in stock. (Don't hold your breath)
So let's try to direct you to an economical build, or at least as cost-effective as your local supplier will allow!
To start you do not need to build your bell completely out of firebrick.
Only above the riser is firebrick needed, that screaming hot air that your batch produces starts cooling instantly after leaving the riser.
Regular solid clay brick is all you need for 80% of your build.
Your batch box core is of course all firebrick. Everything else is clay brick.
In the US, some states require a full double skin.
Although making it more resistant to any (leakage) in your home it is certainly not a requirement! (except in those states)
A warmed-up rocket stove will have negative pressure, any tiny air leak will pull air into your system, and not leak it into your home.
So in my opinion skip building a double skin.
What you do want, is dry bagged clay and bunches of clean medium-grade sand. Any rocks are a big problem in your clay mortar, if using (free) sand it must be screened first.
It is hard to do, but try not to overthink your build. (most everyone does on a first build!)
This is easy easy, playing like a child in a mud bog. Very messy while building, be prepared to make a clay mess in your home.
Just take it one step at a time, figure out your next step when you get to it. If you try to plan everything out perfectly ahead of time A) it will take way too long and B) you may have no hair left after ripping it all out!
It sounds complicated and scary but believe me it is not!
If you're not sure how to proceed then ask us for help, we are doing our best to switch every wood burner in the world over to an RMH... But it takes time!
Everyone like yourself, who successfully builds and LOVES their new Rocket becomes the best advertising we can have.
After you are a happy successful rocket builder you will be telling complete strangers all about RMHs and offering to display yours and maybe even offering to help build!
Again Congratulations on the first step to becoming a ROCKET SCIENTIST!
For all your Montana Masonry Heater parts (also known as) Rocket Mass heater parts.
Visit me at
dragontechrmh.com Once you go brick you will never go back!