This is an inspirational project that is worth looking in to.

I would love to see one working, to work on the construction of one and to have one in my home … if I could only find the space for it … we appear to have downsized ourselves out of this possibility.

Here is an excellent website on the subject. Lots of description, pictures and video. I include the first page or so. Click on the heading below to go see the whole, grand thing. – Ted

rocket stove mass heater

rocket mass heaters in a nutshell:

• heat your home with 80% to 90% less wood
• exhaust is nearly pure steam and CO2 (a little smoke at the beginning)
• the heat from one fire can last for days
• you can build one in a day and half
• folks have built them spending less than $20

the verbose details on rocket mass heaters:

This could be the cleanest and most sustainable way to heat a conventional home. Some people have reported that they heat their home with nothing more than the dead branches that fall off the trees in their yard. And they burn so clean, that a lot of sneaky people are using them illegally, in cities, without detection.

When somebody first told me about rocket mass heaters, none of it made sense. The fire burns sideways? No smoke? If a conventional wood stove is 75% efficient, doesn’t that mean the most wood you could possibly save is something like 25%? How do you have a big hole right over the fire and not have the house fill with smoke? I was skeptical.

And then I saw one in action. The fire really does burn sideways. The exhaust is near room temperature – and very clean. The smoke doesn’t come back up because a huge amount of air is getting sucked into the wood hole. Neat! I sat on one that had not had a fire in it for 24 hours – it was still hot!

how it works:

The sticks stand straight up. Only the bottom ends of the sticks burn. The fire burns sideways. Since the heat riser is insulated, it gets freaky hot. This causes a strong convective current. When the hot gasses hit the barrel, it gives off a lot of heat, which cools the gasses which get much smaller and easier to push around. The gasses that exit are usually just carbon dioxide and steam.

The real magic happens with the heat riser. The strong convective current is what makes the air get sucked in through the wood feed so that the fire burns sideways and the smoke doesn’t come out. It is also the place where it gets so hot that all of the smoke is burned.

——

Here is a book on it, as well as related construction how-to books. Their link and description below:

Welcome to the Web Site of the Book Rocket Mass Heaters: Superefficient Woodstoves YOU Can Build (and snuggle up to) by Ianto Evans and Leslie Jackson

Here is a superefficient wood fired heater you can build for yourself in a weekend for less than a hundred dollars. This book explains in detail exactly how to build one, then how to use it in a range of applications.

We discuss materials: where to find them, what to pay and how to make use of found and recycled parts. The section on fire and fuels is thorough but simple; we tried to keep away from numbers wherever possible.