Kees' cottage rocket

If you put about 2m of flue pipe on that you will be amazed by the difference. Stack effect is critical to performance of all mass heaters, and more so for the small cross sections like this one, where the friction really impedes gas flow.

Everything else about this build looks good to me, and the fact that you're getting a weak draft, but at least in the proper direction, says that this little dragon is begging for a pull on its tail.

HI There


I have 15 x 15 cm and as long as possible into the barrel is I think 54 cm, and the high of the rizer is also of the right dimensions, the barrel on top is
far enough from the output of this rizer, who is as big in diameter as the shimney..

I have 2 meter shimney on it, 15 cm, it is not seen on movie.

The dimensions are as such a little compromised beuase of the barrel but it does burn well.

Wood who is fall into the tunnel is because it where some blocks and did fall there but it did burn well.

I go make a P challel  maybe that helps also.


thanks for advice ..

Scott Weinberg wrote:5 months ago, you said and it appeared you had it working well? Now you say or think it is not?

I had not test it without a shimney and it did burn but also smoke, but now it is complete and it does much better
nut can improved.

go make a P challel and try to make a part on it that cause air turbulence like a metal bend  golf or so.

Did not work well, smoke, and odor, I even myself smell at it, and that is not oke.


The max temp I did reach on top of barrel was 123 degree celcius. this means the afterburning do
not work because if it does, it get a hell lot hotter, it did better when I did make the tunnel 3 cm smaller in
the top and  bottom and left the sides 15 cm, I did see this somewhere in past and also then a pit for the ashes.

You now I can not smoke out nabures and just that was what I did with it, the barrel is also outdoor
and outside it is 10 degree celcius or so.

I think the fire in the tunnen is way to low in temperature, all other stuff is oke, chimney etc. The
rizer is isolated with a ceramic blanket like more people do.

here the burning.

https://youtu.be/ziO7bOsGo-A

Hi all


Did test again after isolate the vloor of the core, it  do make a difference what means I have a to cold
place for the fire to go fully.

I need to make a core with clay, and the potting stuff, for plants so it is isolated.

I had the idea to isolate the core, because I have used 3 cm thick stones a layer of ceramic whool is
maybe a solution?  So I can let the stove in one piece.

see here. This man did use thick stones and have isolated it, with rockwool and ceramic.
https://www.youtube.com/watch?v=fiHpE0h9GiQ

https://youtu.be/s4GMV1T4l9E

Can someone advice me, I need to know if this is the stuff I need for insolated core.

I have bought a bag with brown balls in it, bigger and smaller, it is for plants.

I do not now if there are also other ones, these balls in the bag are very low
weight.

I have the brown ones, what is clay, So perlite is the white stuff

Hi Kees,
I use that (expanded clay) for insulation.
And yes, perlite tends to be white.

Keep in mind that the expanded clay is insulative, but not as much as ceramic fiber or things like that.
So you need to use a thicker layer of it.
I use it for the base under the core, sometimes around the core and often to disconnect a bench from an outside wall.

What exactly are you planning on using it for?

The rocket heater does not well, I have look in the rizer and see flames but it does nog come out afterburning.

It smells and smokes, so I smell also, that is not rockety.

Reason is I think the fire bricks used, these are the non insolated versions and i have only isolate the rizer.

Maybe a batchrocket in such a oilbarrel is better, or make a split into the rizer entree as is with the batchrocket
is a interesting tryout, heat can go higher that way and there is not such a dramatically draw.

Oke thanks.


I go try later a new test, using a slot into uit like the batch rocket does, maybe that cause enough turbulence for better burn.

as when using it now it does suck a lot of air in, and this air is cold because I test outdoors.

Hey Kees,
I built a cottage rocket a while ago. The bottom of the core is not insulated. The rest of the core is, with Rockwool.
Check it out here if you want:
https://permies.com/p/2859774

There's also a video of the first burn.

Hi Kees, where do you live, what is the air temperature?
I have had a quick run through your post but I am not sure exactly what your problem is?
Do you see white or black smoke coming out of the chimney?
What temperature do you see on top the barrel above the riser after the fire has been burning for an hour?

HI James andBenjamin.

Thanks very much for your help

In Netherlands it is 10 degrees, we have a very mild winter.

I have pick a piece of tekst here from a book rocket mass heaters II

C is the cross-sectional area of the horizontal
Burn Tunnel, normally made of brick, in which
most of the burning happens. A single common
brick on edge is about 4 inches high and 2¼" thick
and firebrick is about 4½" x 2½", so arrange bricks
flat or on edge to make up the required height.
C should be the tightest part of the “intestinal”
system. The size of the cross-sectional areas of
all parts of the stove’s internal ducts should never
decrease below that of C. In other words, the crosssectional areas of F, G, H, J, and k should all be
greater than that of C.


Wel I do now now why it does not work well, the cros sectional space in tunnel is 225 cm3  and the rizer
is 176 cm3.

Reason, the riser is round, the tunnel and output is square.

I need to put a layer in, like 5 cm (I have only 5.5) and then the tunnel drops lower then the rizer.

I bet that this is the problem.

here a movie of the burn, it does get better in time but that is mucho to long. there are more.

https://www.youtube.com/watch?v=ziO7bOsGo-A

I second Fox - location matters. If I build a test rocket (or other type) firebox, dry stacked, with no chimney, no insulation, it burns beautifully in dry weather and with dry wood.
When firing in winter humid environment with dry wood, but moistened with dew or fog it may smoke initially or in your case for a longer period.

Cristobal Cristo wrote:I second Fox - location matters. If I build a test rocket (or other type) firebox, dry stacked, with no chimney, no insulation, it burns beautifully in dry weather and with dry wood.
When firing in winter humid environment with dry wood, but moistened with dew or fog it may smoke initially or in your case for a longer period.

Thanks for clarification, Yes it is here quite moisterious, like mist.

But today there was sun, however it is not quite dry weather. I did not tought about that. But do tomorrow correct the burntunnel because this is
very important and I have a way to big one because i did forget to incude the round or squares in calculations.

I have a shimney now, see the movie in previous post.

kees ijpelaar wrote:HI James andBenjamin.


I have pick a piece of tekst here from a book rocket mass heaters II

C is the cross-sectional area of the horizontal
 The size of the cross-sectional areas of
all parts of the stove’s internal ducts should never
decrease below that of C. In other words, the crosssectional areas of F, G, H, J, and k should all be
greater than that of C.


Wel I do now now why it does not work well, the cros sectional space in tunnel is 225 cm3  and the rizer
is 176 cm3.

I went back thrugh your post, and did not find anywhere that you explained what these crossectional areas of F, G, H, J and K are So I am thinking your leaving a lot to us for our imagination.  This is hard to suggest anything, not knowing the details.

And you list cross sectional  space as  cm3,  Where you actually in your calculations needing a description of cm2  Where yours would be listing volume, and other area of opening.  Again, I am just trying to guess what your trying to tell us.  if everyone else has it figured out, great.  

Best of success.

kees ijpelaar wrote:
Wel I do now now why it does not work well, the cros sectional space in tunnel is 225 cm3  and the rizer
is 176 cm3.

Reason, the riser is round, the tunnel and output is square.

Hi Kees. That shouldn’t be a problem. For a fluid the corners don’t really count. So 15cm diameter round is almost the same as 15x15cm square. Doesn’t really make sense at first, but it’s the case. There’s no flow in the corners due to friction.

And I’m with Scott. It would be good if you gave us a reminder of what you’re trying to achieve and in what step you are.

The thread started as a batch box for hot water. Now it’s a j tube cottage rocket that’s outside?

I know you have tried hard to show us the issues you think you might have it is still not very clear to me what your problem is?

If you have built a 6” or 150mm stove then the riser is fine with the same diameter, you do not need to match the fire box square area to the riser square area.

There are hundred maybe a thousand J tubes running just fine with a six inch square fire box, six inch square burn tunnel and a six inch round riser with. No problem at all.

I ready don’t think fitting everything inside a barrel will give you the best performance possible but if you don’t see any smoke out of the chimney and your barrel top is reaching 250c  then you stove is probably working as expected.

If you want more performance then you need to make a more free flowing design using insulating material and a taller barrel.
Because you have used dense fire brick, the stove will take longer to reach peak operating temperature, maybe 30-45 minutes to saturate the bricks.
However if you don’t add insulation then the heat might not rise high enough inside the fire box to satisfy your needs.

Can you buy  vermiculite board where you live? It is very easy to work with and very quick to build with.

Lttle confusion here I see, yes it is cm2 a typo.

The letters K,G etc are from the book rocket mass hearts III, and I have read
some more about the rockets.

The burntunnel needs to be the tightest part, because the rizer is round and the tunnel is square I did make a mistake
who let the tunnel bigger.

I have now make it little smaller as the rizer and it give a better result, now I see flames in the rizer.

Other part I did not right is the burntunnel length, I have not 1/2 lengts, I miss 10 cm, but this is because it is a different
beast an less space in barrel, what I can do is shorten the tunnel, because also in the book the dimensions needs
to fit calculations, and the burntunnel is 48 cm and the rizer is close to 90 cm, I have a gap on top 6 cm.  

I have 6 inch, but did thought it has then all a kind of connection
but I can optimize the burntunnel length and rizer, as long as the tunnel is the smallest part of the system.

Oke, I can shorten the tunnel so it match the rizer of 90 cm, but can als shorten it to 68 cm, the fire will then go deeper
into the rizer and heating much faster, this way I can optimize it as is done in the book, there she also play with the
burntunnel length and rizer length to optimize burning.

regards

Benjamin Dinkel wrote:

kees ijpelaar wrote:
Wel I do now now why it does not work well, the cros sectional space in tunnel is 225 cm3  and the rizer
is 176 cm3.

Reason, the riser is round, the tunnel and output is square.

Hi Kees. That shouldn’t be a problem. For a fluid the corners don’t really count. So 15cm diameter round is almost the same as 15x15cm square. Doesn’t really make sense at first, but it’s the case. There’s no flow in the corners due to friction.

And I’m with Scott. It would be good if you gave us a reminder of what you’re trying to achieve and in what step you are.

The thread started as a batch box for hot water. Now it’s a j tube cottage rocket that’s outside?

Well what I discover is that the rizer is 68 cm and the burn tunnel is 48 cm. did make the rizer longer but is close to top.

I go make the burn tunnel  shorter so it match with the rizer later, so also the fire get into the rizer and not in the tunnel like now happens.


The book roacket mass heaters do state that the tunnel is the smallest part, also with square or round rizers.

C is the burntunnel in the book see attachment need smaller then the rest.

I go just test all, if nabure is quite but I have trouble with her who is heavy anti woodfires.

kees ijpelaar wrote:

The book roacket mass heaters do state that the tunnel is the smallest part, also with square or round rizers.

C is the burntunnel in the book see attachment need smaller then the rest.

I go just test all, if nabure is quite but I have trouble with her who is heavy anti woodfires.

I think I would toss what ever book your referring to, and use the well published and PROVEN numbers on this site.  The J-tube with the right numbers simply works well if your able to keep feeding it. Pretty hard to get around that fact, if you want something that works on the first go,  it would seem relavent to go with proven numbers.

Hi Kees, so sorry you are having so many frustrations.  It’s been a year now that you’ve been working on getting a rocket stove hasn’t it?

There’s so much that goes into a wood stove, and so much more for a rocket stove.

I wonder if you want to look into buying plans for a riser-less rocket stove from Matt Walker.  He has several designs.

https://walkerstoves.com/shop/

When I finally get the support built, I plan to use one of Matt’s plans inside my house.  I don’t think I could live with the frustration you have endured.  Matt’s planns tell you brick by brick exactly how to build, and I think he has a good track record and possibly a good guarantee.

The rocket stove is complex, and you started with complex modifications.  

As hard as you have worked, I really hope you finally get a nice rockety rocket! And SOON. Good luck!

Thekla McDaniels wrote:Hi Kees, so sorry you are having so many frustrations.  It’s been a year now that you’ve been working on getting a rocket stove hasn’t it?

There’s so much that goes into a wood stove, and so much more for a rocket stove.

I wonder if you want to look into buying plans for a riser-less rocket stove from Matt Walker.  He has several designs.

https://walkerstoves.com/shop/

When I finally get the support built, I plan to use one of Matt’s plans inside my house.  I don’t think I could live with the frustration you have endured.  Matt’s planns tell you brick by brick exactly how to build, and I think he has a good track record and possibly a good guarantee.

The rocket stove is complex, and you started with complex modifications.  

As hard as you have worked, I really hope you finally get a nice rockety rocket! And SOON. Good luck!

Ap people here I wish a happy new year and at least more peace in the world.


Concerns the rocket, I have not worked every day on it and I have also did not take a year or so, it starts with ideas but had
also other hobby,s to do and I drown very easy in them, so do stall things.

I have done the rocket and it does well, getting almost 500 degrees on the top in cold outside tst who is very good.

I did make the burn tunnen little smaller as the rizer, because rizer is round and tunnel is square it was bigger, and
as people say that is no problem, it is poberly is, as I did see on the book, the tunnel there is also little smaller, even with
same dimensions for rizer and tunnel.



I can use it now, these are very nice for Oekraïne, easy to make laughing at the russians who try to set them in the cold.

Have nice days, Here it is white of the snow. And yes almost forget, what do I use to prevent rust on top? is there some
stuff for it like in Dutch kachelpoets, what is a tube with black stove fat or what it is called in englisch.

That’s great news, Kees.  Congratulations!  Enjoy

Thanks


Needs to beause of the cold here is present, and coming week as boracast is right it can go
as low as -14 degree.

nice pictures though.