Monday, February 17, 2014

Prepare for Liftoff! (With a Rocket Mass Stove)

Oh that Keith. The first time he mentioned a rocket mass stove to me I thought he was trying to live out some boyhood astronaut dream of his.

Turns out he was referring to heat. The kind of heat that just might meet our needs in the new not yet built earth covered home we are planning for the Poor Farm.

Originating in India I am told as well as other third world countries, the rocket stove is a very basic way of cooking using small amounts of wood and minimal hardware with the primary part of the stove being a metal barrel. In fact the fuel needed comes in the form of small diameter twigs that can be harvested with pruning sheers vs the gas guzzling, somewhat dangerous chainsaws.

A very basic rocket stove without the mass heater

You see standard wood stoves waste much of the heat and wood energy when they burn, with a large portion of it going up the chimney as hot smoke. A burns efficiently – converting nearly all of the fuel into CO2 and water, including the smoke. It also stores it’s thermal energy in a “battery”,  a bench that stores the heat from the fire and releases it slowly over the course of the day.  The stove can burn both logs and scrap wood and the best part is, it can heat the same space as a regular wood stove with 1/4 of the wood!When built properly the air intake makes a sort of rocket exhaust sound and thus the name of the stove. The idea is taken further by rigging up additional pipes that extend from the rocket stove where the heat travels.

If you cover up this ductwork with mass like adobe or brick in the shape of a bed, couch or loveseat you get not only a stove that warms your home and cooks food but one that also will provide you with a very nice place to sit. The heat will emote from the "mass" part of the stove for 12-18 hours AFTER the fire has been extinguished.

Some friends of ours built one about 3 years ago and we visited them last week to check it out. But of course I forgot my camera but it was indeed very cool (to look at) and very warm (to sit on). But wait! The very stove they built was featured on the Midwest Permaculture Sight. So I'm able to share it with you after all.

Wayne and Bev Malchows Rocket Mass Stove
and check out that beautiful poured concrete floor!
Is that not so cool? I was sold and cannot wait to build out own in our new home. Heat costs will be minimal since the house will be underground and we've been told that earth homes retain heat so well we may only need to fire up our rocket mass stove about every three days.

That means you can heat a 1200 square foot home for pennies a day. Provided your home is well insulated.

And the metal barrel can even be covered with the matching adobe seen on the bench. Seems they must be replaced about every five years (just the barrel) but if you built it with a stainless steel barrel you may be good for almost 15 years.

I'll be thrilled if I'm good for another 15 years myself.
But if I use it as a primary cooking source how will we prepare food on the days the stove is not running? And what about in the summer when our cool is keeping the home cool and not warm?
We are thinking we might build a little add on summer kitchen. Or put in a small electric stove. We shall see.

In the meantime having a blast looking on line at all the fun rocket mass stove designs. So let me know. Are you familiar with these? Ever built one?  Did you love it ? Hate it? Would enjoy hearing from you rocket mass stove folks out there.


  1. Dan has been researching this very thing. Rather than making the thermal mass some sort of seating thingy, he's wondering about using it as radiant heat under the floor. We're planning to experiment sometime this year.

  2. That sounds very interesting. Are you blogging about it yet? I better go check. I love the idea of making my mass big enough to be an extra guest bed when needed or maybe thick enough it could be used in two rooms separating by a wall. Never thought of the floor being heated. Gosh my followers are brilliant!

  3. That sounds so interesting; I shall research further. My son would love it for our barn conversion.

  4. I've heard of them but haven't used them nor have i seen any in real life. I'm intrigued by the idea.