rocket mass heater

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kees53

ArboristSite Lurker
Joined
Jan 19, 2010
Messages
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Location
the netherlands
Hi All


I go soon try a rocket mass heater build, I do not build the sit place, only the rocket stove itselfs, maybe I do use brick in stead of a drum, I have seen here a stainless steel version of it but stones will keep heat longer.

I have brick for 1 euro piece 20.7 x 11 x 6.2 cm.

So my question is are these usable qua dimensions? I have a shimney not wider then 11.5 cm 6 .5 meters high.

So I need a riser also the same dimensions? the feeder is 11 cm? little small or will it work?.

I have now this one, with tubes build in myself.

http://s182.photobucket.com/user/kees50/media/kachel5_zps0ca413e6.jpg.html

thanks in advance.

kees
 
i've read a little about rocket stoves or jet stoves as some are called. they allegedly produce much heat with very little wood.

i'm going to try and find where i read about them.....

nicodermus.jpg


rocket-mass-heater-diagram.png
 
i've read a little about rocket stoves or jet stoves as some are called. they allegedly produce much heat with very little wood.

i'm going to try and find where i read about them.....

Looks like a fancified rework of the Hill Boiler from back in the '70s, minus a few very important parts. Inc. secondary air feed.

Big difference: Richard Hill (Prof. Mechanical Engineering UMO) designed biomass heaters that worked, efficiently and cleanly.
 
I have seen people do use fire concrete for making the riser and filler unit for a rocket, is this the better
way, beacuase of insulation of vertical burn chamber, for me it looks a more easy way and more precies
and flat so it do not leak on barrel..

I go make a electric shimney fan myself, with regulator this can compensate the draft and when fire it, it will never put smoke in the home again, after it is warm I put it slower only compensate the smaller shimney pipe, it is also possible to write a little pic program who can regulate this by measure the oxigen with a car lambda sonde.

regards

kees
 
from some of the drawings i saw, the fan to assist in the draft was attached on a 45 degree elbow which was attached to the flue. that way, the fan would never be in the hot gasses. i guess once the unit got burning you would not need the fan any more and it could be shut down.

i'd like to know more about the efficiency of these. all the photos show just a bundle of twigs in the fire. how long could they last and how difficult is it to control the amount of air via a damper? since you need the draft under the fire and to prevent smoke from rising up, you would need a hot fire to keep the air movement.
 
A rocket mass heater may not be limit by a damper, it needs burn full for clean combustion, there is
a brick build version who get 250 oC on top, and after burn it last long heating.

Do you have picture of that system with elbow ventilator.

I have a 8.3 meter high shimney, I can do it on top of it.

http://static.mijnwebwinkel.nl/winkel/schoorsteenwinkel/full25610037_a.jpg

this type must be on top.
 
Did some drawns in sketchup, I see I have to be carefull, bottom is insolated with or ceramic board of fermiculite.

these measurements are the best for the firebricks I can buy for cheap, 1 euro piece and are 20.7 x 11 x 6.2 cm

rocketmassheater1_zps49aa2af6.jpg


rocketmassheater2_zps8cb6a569.jpg


rocketmassheater3_zps18a36004.jpg


rocketmassheater4_zps6deab2be.jpg


rocketmassheater5_zpsa3a2ae76.jpg
 
I prototyped 8-12 of these in my garage and tested them in my backyard last winter.

They are, as a class, very efficient and run very hot. Probably will be regulated in the US under the recently proposed new EPA regs, there were previously exempted as stoves with and air:fuel ratio in excess of 50:1 by weight. If you are going to bring one inside the house, definitely plan on using an outside air intake, or cold air intake or whatever you want to call it, don't feed it warm air from inside the house cause it is going to suck you dry.

There is a .pdf about rocket stoves that has all the math worked out for a first time builder. The .pdf is about US$15, widely available from multiple links on www.permies.com and absolutely worth the money to save repeating mistakes that have already been made. Critical dimension is throat diameter. Once you pick a throat diameter the length and diameter of the vertical feed down tube is plug and chug, same for the diameter and height of the vertical exhaust.

Supposedly throat diameters at and under 4" are "finicky". I spent a bunch of time on a 3 5/8" throat diameter stove last winter. It could be a good size for a cottage around 1200sqft with good airseals and good insulation. To get it running I had to feed it bone dry wood split to about the size of my pinky finger, maybe 1/2" (1cm) in diameter. "Zero rocket stove" should hit on google.

That SOB was finicky on a good day and higher maintenance than a Hollywood starlet on the other days. I finally got it hot enough to really take off and go "whooooooosh" instead of just roaring, one time. I just don't have access to wood with straight enough grain to split enough wood small enough to feed that thing.

My 6" throat diameter prototypes did a lot better, but I was still feeding them wood about the size of a 2x2 split in half. Maybe 1x2 or 1x3cm. Ridiculously small splits.

The other short coming, as already anticipated by coldfront, is most of the heat from a rocket stove is in the exhaust gas. Certainly they run good cold and much better when the material of the stove is hot; but even then most of the generated heat is in the exhaust gas and needs some kind of masonry or adobe heatsink to be captured.

Primary tuning difficulty is ash production. As ash builds up at the first corner where the vertical feed meets the horizontal throat, the critical dimension - throat diameter- changes, and changes for the worse. If you feed them too much wood ash builds up quick and the stove gets sluggish, which leads to more ash build up, then it drops out of secondary burn and eventually the fool thing just stalls, smoking up your living room.

Rockets are a great idea and someone is going to make a million dollars on them when they get it figured out. In the meantime I'll stick with my catalytic equipped Blaze King, feed it big gnarly knotty chunks that can't be split under 8" max dimension and play with rockets in the back garden as a hobby. A properly sized masonry heater with a modern design that supports secondary combustion is much better understood beast for now.

Don't mean to sound discouraging OP. try googling up 'P-channel" or "Peter Channel", should take you to another guy, in the Netherlands no less, who is fooling with rockets because there are so few trees in Holland. He is heating quite a few square feet of house with just busted up shipping pallets.
 
Thanks pointdexter.

Suck me dry ehhh, well then my wife has nothing to do.

Oke, serious I have a shimney who is 11 cm wide, and 8.3 meters high, Si I need a rocket that diameter whole along, I did thought by
using a fan on the shimney for it so it also can be used for starting, however these ventilators are here very expensive so make
one myself is a option.

This moment I have a woodstove look like a gas stove uit years 60 and did build in a englander 30-NC secondairy air intake, but struggle
a little of primairy air is also needed here, I have now three air inputs, one original from under the fire, one I have put in is a window
wash version who give air (original he has also air wash but then from the two sides of the door?? is this better then from above?).

The drawns of the rocket is for a second project, this because I think this is the best way to get nabure people out of odor and smoke,
therefore was my stove put in a secondairy tube, but I need mucho to much heat to let it work, and so the house get hot, it is
very good insulated house a la Holland, and that is just airtight, with a rocket I suck it vacuum yes but I can open the windows to
prevent this.

New inserts done



the old insert before, did burn better?? but maybe now it is because of no wind here for weeks..



regards

kees
 
As far as outside air intake I heard the exact opposite. To never use a outside air intake inside a house with a rocket mass heater, it can cause a pressure differential inside house that could cause a back draft, plus it is good to have fresh air circulate inside your house. For $20 I would read the book on them before trying one. http://www.rocketstoves.com/
 
Hi

I have this book, I go read.

Someone has a tip to quit a nabure who do play house on a 1000 watt installation making my live miserable.

You will not now how hard these bass do get in, it is alowed here before 22.00 hour, unbelieveble noisy world
we have to remove that music and installations out of livingrooms who is terroring people.

I do now in usa this is not alowed, but there houses are free standig, here I have a tight wall 2 bricks thick
and 2.40 and 6.5 meters between me and the nabure, this is like a big speaker.

I go emigrate to usa or canade or new sealand more space mor quit.

here listen to it and decide.



Holland have discovered Halloween ;-).



Yes it is a little offtopic but I thought I let now to people who are more natural here, uses this for action aganinst it.

thanks for all the reactions. And now futrher with the burning, and now I do not light that nabure. ;-)

kees
 

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