rocket stove mass heater

rocket mass heaters in a nutshell

rocket mass heater
  • heat your home with 80% to 90% less wood
  • the heat from one fire can last for days
  • you can build one in a day or two
  • folks have built them spending less than $20
  • less CO2 than natural gas or electric heat
  • if you buy the wood, it costs less to operate than natural gas

rocket mass heaters news

the verbose details on rocket mass heaters


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:

rocket stove mass heater

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.

rocket mass heater

Above is a much better image showing the mighty power of the insulated heat riser, reburning the smoke and powering the whole system.

The first picture below represents the most thorough rocket mass heater design I have ever seen. Followed by the rocket mass heater that was created from that design. These are both the products of the leaders in rocket mass heater innovation, Ernie and Erica Wisner, who have built more than 700 rocket mass heaters.

rocket mass heater plan rocket mass heater complete


Is a rocket mass heater cleaner than natural gas heat?



Is a rocket mass heater legal?

Can you cook with a rocket mass heater?

How much does it cost to run?

Are there alternatives to the barrel?

What is "cob"?

How many of these have been built?


How much does it cost to build one

Can it cause carbon monoxide poisoning?

Will it work with a wooden floor?

Can I hire someone to build it for me?

rocket mass heater vs. conventional wood stove

conventional wood stove


rocket mass heater house


I've now given presentations and taught people how to make these. The question I am most often asked is: "If my current wood stove is 75% efficient, it seems the most room for improvement is about 25%. But you say you can heat a home with a tenth of the wood. Isn't that claiming that a rocket mass heater is 750% efficient? Wouldn't 100% efficient be the maximum?" There are two ways to answer this.

  2. Let's do the math.
    • A rating of "75% efficient" does not account for some of the heat that goes up the chimney to remove the smoke. The testing labs will use a number of either 14% or 16% for smoke going up the chimney. So the 75% number is actually 59%. Saying 75% is allowed and sells more wood stoves.


Here is Ernie talking about how replacing a conventional wood stove with a rocket mass heater and how he now uses 1/8 of the wood he used to use:

Better Wood Heat: DIY Rocket Mass Heaters

This 4-DVD set about rocket mass heaters came out September 2016.

How to Build a Rocket Mass Heater

Here's the trailer for the new DVD set.

CLICK HERE for more information

get free rocket mass heater goodies

If you sign up for the dailyish email right now, you will get the most popular Rocket Mass Heater design plans on the market, The 6" Annex Variation! Ernie and Erica usually sell these bad boys for 15 dollars but they are sharing this info with you in hopes of building support for their upcoming kickstarter which will bring rocket mass heater knowledge to millions of people!

Click Here To Get Instant Access!

Wood Burning Stoves 2.0 4-DVD set

After years of polishing this article, giving presentations and teaching workshops .... Ernie, Erica and I set up a special workshop to mash in everything about rocket mass heaters, rocket stoves, etc. just so that we could video it and put it all into this 4-DVD set.

wood burning stoves dvd set

Trailer for the 4-DVD rocket mass heater set:

Find out more here

rocket mass heaters in action

When I first learned about rocket mass heaters, I desperately needed to see a video because what I was told was so .... different. There was nothing! So I now have lots of videos so people can see for themselves, the things that seem so new. This is just a few of the videos.

A short video making the rocket mass heater exhaust aspect really clear:

A general tour of 12 rocket mass heaters:

This second video is a day and a half workshop on building rocket mass heaters compressed into ten minutes:

My first attempt at building a rocket mass heater without somebody to guide me. This is an attempt at a semi-portable rocket mass heater. Plus a nice burn demo.

The latest from Ernie and Erica - complete with some innovations. This video focuses on how efficient a wood burning stove can be.

Building Plans

If these rocket stoves are of interest of you, the smartest next step is probably to get a set of plans that closely resembles what you are thinking of designing. These plans are proven designs that Ernie and Erica Wisner, the leading rocket stove innovators, have developed and tested.

6 Inch Rocket Mass Heater Plans

Annex Variation

These have been the all time most popular plans up to date.They are for an L-shaped heated bench. 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.

Click here for more details!

Daybed with Bypass

These plans are for a duct-heated, small heater that warms an 11 x 11 (120 sf) guest cottage in Portland, OR. A bypass from manifold to chimney allows priming the heater more easily for cold starts. Instead of a bench, the mass makes up a platform for a bed!

Click here for more details!

8 Inch Rocket Mass Heater Plans

Bonny Convection Bench

This is for an 8" duct diameter with room-air circulation channels over reinforced wood flow. This large system currently heats a 3-story, multi-family house in a cool coastal valley. Reinforcement and built-in air channels protect the existing hardwood floor while providing passive circulation of warm air to the rest of the house.

Click here for more details!

Cabin Variation

This plan is for a duct-heated compact 8" diameter rocket mass heater, with a 3.5' x 9' footprint on concrete slab floor. The original installation heats a 840-sf cottage in alpine/high-desert climate near the Canadian border (snow Oct to April) on about one to 1.5 cords of wood per winter.

Click here for more details!

Rocket Mass Heater Operation and Maintenance Manual

This manual includes sample drawings, fill-in-the-blank areas for site-specific details, operation and maintenance logs, and standard instructions for how to light, clean, and maintain the heater. There is also a troubleshooting section that addresses problems that may come up due to design, maintenance, or operational oversights. The total length is about 20 pages (updates will be substituted from time to time).

Click here for more details!

The Art of Fire by Ernie and Erica Wisner

This 40-page booklet is intended as a general introduction for anyone who wants to learn about fire. It will be entertaining for those who've heated with wood for years, and especially useful for those who are just starting. Offers many insights for campfire cooking, fire safety, and other survival skills.

Click here for more details!

Rocket Mass Heater Builder's Guide - DRAFT 2014

This is a ROUGH DRAFT of our complete, technical guide to building rocket mass heaters. Our Builder's Guide offers specific, step-by-step building instructions and dimensions for our most popular type of rocket mass heater (an 8" design with J-type firebox), and detailed technical appendices covering various design and materials options.

Click here for more details!

Ernie and Erica's EVERYTHING combo

With this combo you get huge savings in the ol' money column by getting ALL of the plans above
PLUS chapter 4 of Rocket Mass Heater Builder's Guide
PLUS The Art of Fire
PLUS Simple Shelter ideas
PLUS Double-Chamber Earthen Oven plans

Click here for more details!

Building Ideas

Several people have been able to scrounge parts over several months so that the construction cost ends up near zero. Here are some of the materials you might want to look for, complete with links to be able to purchase them in case you cannot find them otherwise:

Here is another rocket mass heater workshop. This one is building the rocket mass heater into a greenhouse

Discussion thread at permies: greenhouse with a rocket mass heater

And this one shows the rocket mass heater barrel prep. Complete with an excellent demonstration of the rockety stuff - check out that smoke reburn!

Here is Ernie's conventional wood stove / rocket mass heater hybrid, which gives a lot of info on how a rocket mass heater can heat a space with 90% less wood than a conventional wood stove:

This is my grand video on my portable rocket mass heater. This features four huge innovations: a wood frame aesthetic (a bit rough, but the trail is now blazed for better wood workers); portable (can be taken apart and put on truck in less than an hour; can be taken off of a truck and built in a little over an hour); a heat riser that goes all the way to the ground instead of sitting on bricks; the thermal mass is a collection of pea gravel and river rock (that allows air to pass through) instead of cob. This video has a lot of details of construction.


The Rocket Mass Heater Builder's Guide by Erica and Ernie Wisner

Read more about it and get the book here.

Finally - a comprehensive book about rocket mass heaters! This should put an end to the freak shows of flaming death showing up on YouTube mislabeled as rocket mass heaters - and put an end to getting the same questions asked over and over again. We can start every answer with,

"Have you read The Rocket Mass Heater Builder's Guide?"

Rocket Mass Heaters by Ianto Evans

Read reviews from Permies and get the book here.

This is a delicious book to read and understand HOW rocket mass heaters work and WHY rocket mass heaters work so well. Ianto is the inventor of rocket mass heaters, and he does an excellent job of telling the story.

rocket mass heater podcasts

As I was designing my portable rocket mass heater innovations, I called Ernie and Erica several times. After all, they know far more than I do. After the great Earth Day success I recorded a podcast with them. Not only to have a podcast loaded with rocket mass heater / rocket stove info, but to gloat a bit about the success of my innovation. This was my very first podcast about rocket mass heaters!

Since then, I have recorded over a dozen podcasts about rocket mass heaters and you can get them in a giant bundle here:


The good artwork here is done by Daniel Van Tassell although Daniel insists that I credit Adriana Stagnaro for a collaborative effort in the permies forums.



Many thanks!