evidence that rocket mass heaters are efficient

A rocket mass heater heats with one tenth the wood of a conventional wood stove.  I'm sticking to it.  This has been called a "claim" and "snake oil" and "hype." Hundreds of times?  Thousands?  Others a bit more direct: "lies", "fabricated bullshit", "he's just a shill trying to sell his crap."  

I confess that if I said "half the wood" we would probably have ten times more buy in.  But I'm an engineer.  It is 90% less wood.  And to make it worse, I am obsessed with finding ways to make it better still.

Let's start with a video I made where I talk about how I heat a 3 bedroom montana home, all winter with 0.60 cords of wood.  




A review from a guy in the UK after two years.  He replaced a wood stove and crappy couch with a rocket mass heater.  He said that with the wood stove it used a LOT of wood and they were still constantly cold.  Now they use a quarter of the wood and they are warm.




I tried to explain HOW it is so efficient here




I thought it would be good to have a thread with people sharing their rocket mass heater stories about how much wood they use to heat their home.

And here is a beautiful rocket mass heater build that is done very well.  Free on youtube.  Thus removing all profit from me - because the key is that rocket mass heater stuff is more important than the pennies i get from selling my movies.

Hi Paul. So I heard you talk about this RMH somewhere in Scotland (during the backathon). I was curious, because Montana is too far away from me, Scotland is closer. In the second backathon live (which I did not see live, but afterwards) you mentioned it again. And you said you wrote a thread in which there's a YT video. I found this thread.

I watched the video. I went to their YT channel. Then there I followed the link to their website.

It is still a little far for a bicycle trip from the Netherlands ... in the most Northern part of Scotland ... but this is an ideal spot to visit! It's a permaculture site (a 'croft', that's what you would call a farm), but they have 'camping pods' too. And the site has a wonderful view on a Loch!
Caithness Camping Pods

If it is of any help ...



More here


This thread is about evidence of the claims that rocket mass heaters are so efficient.  I am trying to contemplate how I might be able to further prove this.  Maybe a video with tracking thermometers showing a day of use. One inside and one outside.  Maybe starting with 8pm and going for 24 hours.  And showing the amount of wood burned.  

Inge Leonora-den Ouden wrote:Hi Paul. So I heard you talk about this RMH somewhere in Scotland (during the backathon). I was curious, because Montana is too far away from me, Scotland is closer. In the second backathon live (which I did not see live, but afterwards) you mentioned it again. And you said you wrote a thread in which there's a YT video. I found this thread.

I watched the video. I went to their YT channel. Then there I followed the link to their website.

It is still a little far for a bicycle trip from the Netherlands ... in the most Northern part of Scotland ... but this is an ideal spot to visit! It's a permaculture site (a 'croft', that's what you would call a farm), but they have 'camping pods' too. And the site has a wonderful view on a Loch!
Caithness Camping Pods

Hi Inge, if you want to see RMH's working in real life there are also many to see in the Netherlands. I've seen several over the years built by a group called MasConMenos for different eco community's but there are also other Dutch people building them like for example Peter van den Berg. Most of the builders from MasConMenos live in a community in the northern part of Groningen called StaatjeVrij where you can find several RMH's. It's a place a bit like wheaton labs where they experiment and organize a lot of stuff. https://masconmenos.nl/ https://www.woldwijk.nl/staatjevrij/

Hi, does anyone know of any existing RMHs in northern France area ( we are just north of Paris)?
I’d like to see one in operation and discuss real life results before building one at our place.
Thanks,
Dave
Chacrise France

Dave, this guy is a forum member:

Satamax Antone, French side of the Italian border, 3 hours from Marseille, 1 hour from Grenoble. 1 hour from Torino. Grumpy old fart, who only does what he wants, when he wants. Hard to deal with. But if your project tickles his fancy. The outcome might be real nice!

Here is another resource listed:

Yasin Gach, France, website https://uzume.fr/

https://permies.com/w/rmh-builders-list

Dave Way wrote:Hi, does anyone know of any existing RMHs in northern France area ( we are just north of Paris)?
I’d like to see one in operation and discuss real life results before building one at our place.
Thanks,
Dave
Chacrise France

Hello there from near Grenoble.

Another useful contact is http://www.feufollet.org/le-feu-de-bois/
Under their Ressources section, there are a load of links to places like oxalis and all jolly useful.

Passerelle Eco, little subscription mag and website good for looking for contacts for all sorts of reasons, company on a road trip, setting up a farmstead, participative building projects, non violet communication etc etc. As well as articles on permy topics.

I’ve lived with theRMH for 2 years now, rebuild this summer to increase the height of the internal chimney.
I confess that the bench has never been as hot as some benches that I’ve met.
Is it too much draft and wood not dry enough, big stone walls sucking up the heat.
There have been surprising smoke blow back moments for no apparent reason, fire twirling round the feed tube, no evident blockages. It’s a learning experience and getting better.
I’ll just keep splitting those logs, for now, with occasional head scratching moments.
And yes, a Peter Panel is something I think about.

Is the effort worth it?
A hesitant yes, a definite improvent on the previous free standing woodstove with a pretty and large picture window much like a tv screen and a real wood guzzler.

Thank you for your question, an opportunity for me to vent and forward and onward.
Best wishes, biochar blessings,
Marie-Helene

I used my rocket mass heater solely one year, sw Missouri zone 6b. Heating started in October and ended in may. Well insulated house, built for a rocketmass heater. Used 1.2 to 1.3 cords that winter

Eric Hammond wrote:I used my rocket mass heater solely one year, sw Missouri zone 6b. Heating started in October and ended in may. Well insulated house, built for a rocketmass heater. Used 1.2 to 1.3 cords that winter

I guess since you built the home with the RMH in mind, then you don't have any amount of cordwood burned in a conventional woodstove to compare?

What is the square footage of your home?  

Roberto pokachinni wrote:

Eric Hammond wrote:I used my rocket mass heater solely one year, sw Missouri zone 6b. Heating started in October and ended in may. Well insulated house, built for a rocketmass heater. Used 1.2 to 1.3 cords that winter

I guess since you built the home with the RMH in mind, then you don't have any amount of cordwood burned in a conventional woodstove to compare?

What is the square footage of your home?  

You’re correct, I have no baseline to compare it to.

The footprint of the downstairs is 40x20, so roughly 800 square feet. Directly above the RMH is a big opening to the 2nd floor that I would say is 12x12 with a ceiling fan above it to help distribute warm air. The opening leads to a hallway on the second floor with all the bedrooms and then the stairs are on the opposite end of the house so basically cold air can fall down the stairs and get pulled back up at the other end where the RMH is. It actually seems to work really well. I’d say the upstairs is probably closer to 500 sq feet when I subtract the openings and I have a big unheated storage area on the upstairs, so roughly a house sized at 1300 sq ft heated walkable usable space.

The one thing I didn’t understand about heating with wood was I had in my mind that you burnt wood on snowy days.  I never really thought you would need a fire on a 60 degree day, but if your house is cold and you want it warmer, you gotta burn a fire to bring the temp up, so what I thought going in was 3 maybe 4 months of usage turned out to actually be 7 to 8

I showed the second video to my husband and I think he is definitely warming to the idea. So far it has been my proposal, but I can't exactly dig up the living room floor without him noticing! However he watched Andrew's build video without being prompted and thought it was great. The thought of a warm house is so beguiling at this time of year!

Dave Way wrote:Hi, does anyone know of any existing RMHs in northern France area ( we are just north of Paris)?

How about Central France? I've got some pictures of the build on my website (it's the last item on the Gallery page: https://www.la-darnoire.com/gallery.shtml
)

paul wheaton wrote:If it is of any help ...

(comparison graphic - see above)

More here

This thread is about evidence of the claims that rocket mass heaters are so efficient.  I am trying to contemplate how I might be able to further prove this.  Maybe a video with tracking thermometers showing a day of use. One inside and one outside.  Maybe starting with 8pm and going for 24 hours.  And showing the amount of wood burned.  

Paul, another thing you could add to the RMH table is a row distinguishing the current carbon that is in wood from the fossil carbon that is in fossil fuels. When we talk about carbon footprint (which is a problematic concept in and of itself since it was invented in order to put the emphasis on personal responsibility and away from industry, but it's something we all understand) we can quite legitimately say that using wood for energy is climate neutral, because the carbon the trees took in as they were growing was going back into the atmosphere soon anyway.

The emissions that are getting us into trouble are from the atmosphere of 300 million years ago, before white rot fungi evolved the enzyme that digests lignin (which is why there are no coal deposits younger than that...only peat). Cycling what's in the atmosphere is not a big deal and if burning today's biomass means avoiding burning ancient biomass, it's a win-win.

Rob Martin wrote:I've got some pictures of the build on my website (it's the last item on the Gallery page

Excellent build record - thanks Rob for sharing! It looks like you have some other interesting projects there too, I'm looking forwards to checking out your cider press for example...

What I don’t understand is there are only so many BTU’ per pound of wood and I see calculations out there to figure how many BTU’s you need to heat your home. When I see the claims that RMH is 1/10 the wood I don’t see how that is possible BTU wise? Maybe it has to do with what you call a conventional wood stove? I see many new EPA approved wood stove with HHV efficiency at 80% now a days, isn’t that close to the efficiency of RMH’s?

My wood stove is 75% efficient and I heat about 1000 sq ft in N Wis on 2-3 cords of wood. If I had a RMH your claiming I should be able to heat my cabin with less than a cord of wood? I did stack a good 1800 lbs of concrete pavers around the stove to help even out the heat spikes and I like how that’s working out. I usually only have to feed my stove every 12 hours with about a 30lb load of wood on a normal winters day.