Yep that's right, the largest rocket mass heater in the world! Oh no, sorry I don't have it, I was hoping to catch someones attention and see theirs. I want to find out the extent to which a rocket mass heater can be stretched, near to where we live (just moved in) here in Cornwall, England is a very large commercial plant grower. They have offered to show us around on Monday 10th December, next week and I would be a happy little bunny wabbit if I could offer them suggestions (if needed) as to how they could use rocket mass heaters to heat the ground upon which the stuff they grow that needs more heat can get it. If that makes sense. So in other words, how far can say a 200ltr barrel rocket stove heat be dragged ( by fan) before the heat dissapates? And, how large is the largest rocket mass heater in the world? I've you tubed it, but nothing spectaculer comes up.

And, how large is it feasable to build a rocket mass heater to heat a massive ground area of say an acre with underground trenches?

All your lovely ideas will be very much apreciated. Thanks people

Hi Barry;   Welcome to Permies!

I'm afraid that you will not succeed with reliably heating the earth... its too big...Any heat you made would disapate faster than you could produse it.

There must be insulation of some kind under a rmh  to keep the earth from stealing the heat.

How large a rmh has been built?  Well  I have heard talk of 10"-12" J tubes and in the batch boxes only 8" and smaller. I think you could build larger but I haven't seen one.

Rmh's have a better uses...  sit on one, make a day bed , sleep warm at night knowing you will not have a chimney fire .... because you have no fire all night! Burn less wood , spend more time with your family!

They really are not designed for large scale industrial use.

Howdy Barry, welcome to permies!

HERE is a link to all of the rockets at Paul Wheatons lab. There are a couple that might give you some ideas. Maybe the "bun warmer" or the "season extender" ?Check it out!

thomas rubino wrote:

How large a rmh has been built?  Well  I have heard talk of 10"-12" J tubes and in the batch boxes only 8" and smaller. I think you could build larger but I haven't seen one.

J bigger than 8, i can't recall to  have seen one. Thought i've got no brain.

Batch, well, i have a  8.66 (220mm)  https://permies.com/t/44806/Cobbling-workshop-heater

There is Ericaus, who has a ten incher  http://donkey32.proboards.com/thread/1890/inch-batch-bell-rocket-heater  Tho, i don't know if it has been lit yet.

And Alex Harpin, who has a 8.5 batch http://donkey32.proboards.com/thread/1973/8-215mm-double-bells-built

That's all i can remember from the top of my head.

thomas rubino wrote:How large a rmh has been built?  Well  I have heard talk of 10"-12" J tubes and in the batch boxes only 8" and smaller.

There's one (open) batch box in Germany sized at 10" (25 cm) and a 12.6" (32 cm) one in Argentina built in a brick-drying facility. No pictures of that latter one, sorry.

Could the Roman hypocaust systems that were used to heat some of their buildings be considered as a form of RMH?  At least a distant cousin?

https://en.wikipedia.org/wiki/Hypocaust

I realize these have some differing design features, but the Korean Ondol has some similar features too, no?  https://en.wikipedia.org/wiki/Ondol



They built the fires in a kitchen and then heated the mass in an adjacent room before having the smoke rise up and leave through a chimney.

One noteworthy part of the Wikipedia article:  The dol bed, or stone bed, is a manufactured bed that has the same heating effect as ondol and is purported to have health benefits. The dol bed industry is estimated to be worth 100 billion Korean won, comprising 30 to 40 percent of the entire bed industry in South Korea; dol beds are most popular with middle-aged people in their 40s and 50s.

So RMH beds have health benefits!!!  Since I'm in my 40s I should be all over that.

Unlike the Rockets, neither were meant to burn clean.

Lovely jubbly guys! Thank you so much. Not being the engineer type and having looked at RMH's for years and never being in a position (yet) to build one it seemed possible that as the mass grew in size, so the RMH could grow to match it. I'll have a look at the links now, thanks again evryone.
I did see a chinese/korean/japanese (can't remember and can't find it now) community centre with underfloor heating and it was BIG. The riser was a brick wall (which cracked on first burn) but which was repaired and succeeded in heating the floor. This was done through the conventional method of pipes in trenches, which is costly, I thought earth trenches alone might do it and was interested to find out how big technically it would be possible to go.

So thank you for your comments, very helpful

I don't know for a batch yet. But for a J, i don't think more than 15/18 inches could be done easily. Because the draft might become uneven between all the pieces of wood. And reverse at some spots. Plus, there is dilution of the heat with excess O² and the walls of the burn tunnel and heat riser being soo far that they don't concentrate the heat anymore.

https://himalayanrocketstove.com/burning-plastic-in-rocket-stoves-update/

"Long story short I dedicated my shop ,myself and two paid employies for more than eight weeks to build a two meter diamater round ,five meter above ground with three cyclone exhausts and one meter below ground of fire bricks. This giant rocket stove was our attempt to head off the transfer of all our islands (year round population of about 1000)post consumer paper waste.

Accurately measured by three pyrometers I borrowed from local potters, after a one hour warm up we acheived combustion temperatures over 2200 degrees."

No pictures but they claim it's big.

I would think the biggest Rocket Mass Heater ever built, probably no longer exists because of Bessemer's invention for the modern smelting of iron, but it most likely was used in that capacity.