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Please help: Rocket Stove in greenhouse does not work  RSS feed

 
Michael Baer
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Hello,
My name is Michael I live in Germany at the Baltic Sea.
I am 67 years old married and we have a daughter.
For 2 years I am a pensioner and now have more time for our garden.
A few months ago I came up with the idea for my greenhouse one
Rocket furnace. Unfortunately, there is very little information in Germany.
I hope even if my English is not very good and it surely communicative problems
Will be able to help me here.
My greenhouse is 3.5m x 5m (11.49ft x 16.40ft).
The rocket Stov stands in the middle of the house about 400 mm (17.7 ") deep in the earth.
The exhaust gases are to be passed through the earth and heat the ground.
For the test, I have laid a pipe diameter of 160 mm (6.3 ") 500 mm (19.7") deep.
But I have no train. The stove is smoking.
I would like to adjust pictures but I do not succeedwould
So for today enough.
Best regards
Michael

Oh - it worked!

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Burra Maluca
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On your picture, it says 5000 and 3500.

Does that mean 5 metres and 3.5 metres?

If so, I think there is too much pipe.  The stove won't be able to push the hot gas all the way through that much pipe, especially with all those corners.

What is the diameter of the feed tube and heat riser on the stove?  The greater the diameter, the further it can push, but I think you will still need to reduce the length of the pipes.
 
Michael Baer
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Burra Maluca wrote:On your picture, it says 5000 and 3500.

Does that mean 5 metres and 3.5 metres?


Yes, but in Germany a lot of measurements are given in mm.
Michaei

The furnace output and the pipe in the ground is 160 mm (6.3 ")

Good Morning,
I would now like to show a short video and ask you to see if
The proportions of the individual components are ok.
After assembling, I am almost of the opinion that the combustion chamber
(Quadrangular tube) is too small in relation to the vertical tube.
I wonder if the reason is that the train is too small.
Michael

<Files with the extension .mp4 are not allowed as attachment in the message.>
ok

New trial
<Files with the extension .zip are not allowed as attachment in the message.>

Also as zip not a success. How can I set a short Viedeo.

On the following pictures I show how the smoke exhauster was produced.
The tube diameter is 160 mm (6.3 ")


Abgasleitung-im-Erdreich.jpg
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Rohrstutzen-Rauchabzug2.jpg
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Burra Maluca
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For video you'll need to upload it to youtube or vimeo and then post a link.
 
Michael Baer
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Burra Maluca wrote:For video you'll need to upload it to youtube or vimeo and then post a link.


Thank you for your help. I just uploaded the video on youtube and now I will try to bring it here. Whether it succeeds?
Michael

Oh Prima !!
I'm excited.
Learned something again!!!

I've been trying to get some secrets about rocket stove in the Greenhouse.
It is very difficult for me to understand the technique of heat transfer in the soil.
Therefore, I will now show pictures from the beginning of the project.
Projekt-beginnt.jpg
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Untergrund.jpg
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Platz-f-r-Ofen.jpg
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Michael Baer
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I wish all Forians a happy and peaceful Christmas
Michael
 
Satamax Antone
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Michael, on jour vidéo. I can see an all metal core, non insulated, with a very long burn tunnel and an angled feed. Plus a cyclonic heat riser.  Not a good start for a first build.

And, i wanted to ask, what's your rend pipe?
 
Rick Hannaman
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   Guten tag Michael, is that dutch for good evening? Hope so. Look's like a loooooooooong draw for your exhaust. Any feasible way to pre heat the last few feet of the chimney/flue so as to initiate the flow of hot gas'es? Just a thought.

         Rick in Pantano, Arizona.
         yes the ghost town.
 
Sam Fel
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Perhaps a downdraft fan will help to actively push the heated gases thru the pipe?
 
Michael Baer
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Satamax Antone wrote:Michael, on jour vidéo. I can see an all metal core, non insulated, with a very long burn tunnel and an angled feed. Plus a cyclonic heat riser.  Not a good start for a first build.

And, i wanted to ask, what's your rend pipe?


Hello,
The video was just an attempt. As I said, there is almost no information in Germany
As regards rocket stove.
It is clear to me that there is a certain relationship between the various parts. But I have not yet discovered how that is. Do you understand what I mean. In addition, there is the problem of understanding.
Many terms are inexplicable for me.
For example; what is a
<Rend pipe>
Greeting Michael
 
Michael Baer
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Rick Hannaman wrote:
   Guten tag Michael, is that dutch for good evening? Hope so. Look's like a loooooooooong draw for your exhaust. Any feasible way to pre heat the last few feet of the chimney/flue so as to initiate the flow of hot gas'es? Just a thought.

         Rick in Pantano, Arizona.
         yes the ghost town.


Hello Rick,
Thank you for your support. But I do not understand what you want to explain to me.
What is a
<Loooooooooooong draw> for the output
Yes, that is with the communication.
Greeting Michael
 
Michael Baer
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Sam Fel wrote:Perhaps a downdraft fan will help to actively push the heated gases thru the pipe?


Hello Sam,
Thank you too
To a fan I've already thought synonymous. Now the following question asks me:
Will not burn faster
If I install a fan at the end of the earth line or at the end of the chimney. Besides, how are the exhaust gases. Still so clean?
Greeting Michael
 
Michael Baer
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Good Morning,
Now continue with my project.
On the following pictures
The built-in oven can be seen in the open state. The insulation has been made with perlite. The material is loosely filled, so that I can still make an impression if necessary. At the top, a cover is placed on top and secured by means of flat friction screws.
The additional air supply on the right side of the combustion chamber as well as in the center of the pipe can also be seen.
Greeting Michael


In the foreground you can see my pellet burner
Gute Nacht
Good night
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Ofen-ge-ffnet.jpg
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Glenn Herbert
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An excellent source for information about batch box rocket mass heaters is batchrocket.eu - it is translated into several languages, unfortunately not yet including German, but originally in Dutch - I don't know if that is any better than English for you. Even though you have built something like a J-tube or L-tube, there is information there that could help you.

In general, a standard 6"/150mm J-tube is said to be good for about 30-40 feet (9-13m more or less) of horizontal duct, minus 5' for every elbow. You show about 7 elbows, which kills your safe length. Your combustion chamber is also smaller than 6", so it would not have that much power. I don't think it will ever work well as is. A fan at the chimney end could pull enough air for good combustion, but you would use up all the heat halfway through the ducts and the end would be cold, doing nothing for you.

I think you need to shorten your duct run, and have fewer elbows, and change your combustion core. What you have built breaks a lot of best practices that have been found to work, and has a lot of experiments like the fresh air in the heat riser that have been found to not actually help as much as fresh air right in the burn tunnel.

Replacing all of the duct in the ground if you already have it is a big job, so if you can't do that, I recommend you scrap the steel combustion core and build a firebrick (or even old soft red brick) 6"/150mm batch box according to the dimensions in the batchrocket site. You can still use the heat riser and barrel you have, with the new batch box connected to it.

I do note the pellet feed you show, and if you can only get pellets to burn, you may not be able to use a batch box. If you can get firewood, even small sticks, a batch box burns for an hour without tending, and one or two loads can put a lot of heat into your ducts. A batch box is said to have about twice the heating power of a standard J-tube the same size, and would have much more power than your experimental core.
 
Michael Baer
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Glenn Herbert wrote:An excellent source for information about batch box rocket mass heaters is batchrocket.eu - it is translated into several languages, unfortunately not yet including German, but originally in Dutch - I don't know if that is any better than English for you. Even though you have built something like a J-tube or L-tube, there is information there that could help you.

In general, a standard 6"/150mm J-tube is said to be good for about 30-40 feet (9-13m more or less) of horizontal duct, minus 5' for every elbow. You show about 7 elbows, which kills your safe length. Your combustion chamber is also smaller than 6", so it would not have that much power. I don't think it will ever work well as is. A fan at the chimney end could pull enough air for good combustion, but you would use up all the heat halfway through the ducts and the end would be cold, doing nothing for you.

I think you need to shorten your duct run, and have fewer elbows, and change your combustion core. What you have built breaks a lot of best practices that have been found to work, and has a lot of experiments like the fresh air in the heat riser that have been found to not actually help as much as fresh air right in the burn tunnel.

Replacing all of the duct in the ground if you already have it is a big job, so if you can't do that, I recommend you scrap the steel combustion core and build a firebrick (or even old soft red brick) 6"/150mm batch box according to the dimensions in the batchrocket site. You can still use the heat riser and barrel you have, with the new batch box connected to it.

I do note the pellet feed you show, and if you can only get pellets to burn, you may not be able to use a batch box. If you can get firewood, even small sticks, a batch box burns for an hour without tending, and one or two loads can put a lot of heat into your ducts. A batch box is said to have about twice the heating power of a standard J-tube the same size, and would have much more power than your experimental core.




Hello Glenn,
Thank you for your message. She was very helpful. I have studied the link. In doing so, I have also come across the connections of the individual components. Just expected. It fits nothing to each other! This means I will cut everything apart and reinstall. You write for 30 to 40m
Is a 6 "riser good. Do you mean the length of the soil collector?
If I could not manage the exhaust gases from the furnace directly through the floor, I think the brick wall above to seal and the heat there by fan by the collector to blow. This should work with security.
What is your opinion on the consideration.
Greeting Michael
 
Peter van den Berg
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Hi Michael,
The color of the buried pipe I find a bit suspicious. To my eye, it is the same as the PVC pipe for sewers here in Western Europe. So, just to be sure, that pipe should be metal otherwise you can't expect heat transfer from the pipe to the surrounding soil. Let alone the risk of melting or burning of that pipe.

Another possible snag: in the third picture the vertical exhaust diameter seems to be quite a bit smaller than the rest of the pipes and heater core. You definitely need a proper vertical exhaust pipe, reaching at least above the greenhouse roof and any higher objects in the direct vicinity.

I'll second Glenn's remarks, nearly every aspect of your design is out of the known configurations. When you want to build something that is quanteed to work, stick to the documented and tried solutions. Please note Glenn is talking about 30 to 40 feet, as opposed to 30 to 40 meter, which is 3.3 times as long as feet.
 
M.H. Hilliard
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I've never, ever, had a thing to do with a rocket stove so my comment may be irrelevant. I'm a potter who fires kilns fueled by wood and natural gas and I always have to consider my 'thermal mass' and how that influences the draft of the kiln. So when I saw all of this horizontal flue ( and I know a rocket stove uses a horizontal flame) I immediately thought that the earth is cooling the flame and as a result you get no draft. The earth is sucking up all the heat and you'd have to have an enormous flame. So...that's my 2 cents worth and it's based solely on my experience with fuel burning kilns but the basic principle is similar. I'd run a straight flue right out under the greenhouse wall and shorten it, a lot.
 
Michael Baer
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Peter van den Berg wrote:Hi Michael,
The color of the buried pipe I find a bit suspicious. To my eye, it is the same as the PVC pipe for sewers here in Western Europe. So, just to be sure, that pipe should be metal otherwise you can't expect heat transfer from the pipe to the surrounding soil. Let alone the risk of melting or burning of that pipe.

Another possible snag: in the third picture the vertical exhaust diameter seems to be quite a bit smaller than the rest of the pipes and heater core. You definitely need a proper vertical exhaust pipe, reaching at least above the greenhouse roof and any higher objects in the direct vicinity.

I'll second Glenn's remarks, nearly every aspect of your design is out of the known configurations. When you want to build something that is quanteed to work, stick to the documented and tried solutions. Please note Glenn is talking about 30 to 40 feet, as opposed to 30 to 40 meter, which is 3.3 times as long as feet.


Hi Peter,
I chose my remarks. I just finished your page http://batchrocket.eu/en/building studied. I now realize that all proportions are wrong. I had already told Glenn. That is, I will cut everything apart and build a 5 "furnace for your Calculator, the J will fit into the existing case In the ground, they are KG pipes and they hold 65 ° according to the manufacturer.
It is clear to me that the thermal conductivity of the sheet metal is worse, but I have no way to get it.
Greeting Michael
 
Satamax Antone
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Michael, don't use those pipes. 65c° nowhere near good.
 
Michael Baer
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Satamax Antone wrote:Michael, don't use those pipes. 65c° nowhere near good.


Well, I've understood.
But what are the alternatives?
 
Jenn Andersen
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One more observation, I see your exhaust is far away from your barrel.  I understand from the one rocket mass heater that I helped to build that it is best to place the exhaust close to the barrel so that it reheats the exhaust just before it leaves your system, thereby adding a bit of "pull" as the hot air rises out of the building.
 
Eddie Conna
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Let me preface what I'm about to say with the following disclaimer.  I am NOT an expert in Rocket Mass Heaters, and have never built one.  I have built a few rocket stoves, and I understand the concepts and have studied RMH quite a bit.

it seems to me, that the exhaust is simply far too long.  With an exhaust pipe that long, you don't get the draft you need to pull the exhaust gasses out.  I'd look at that as a possible issue...

 
Hans Quistorff
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2 suggestions: There is a limit as to how much heat can be extracted from the the flue gasses.  They tried heating the ground in the underground house and it did not work the same as yours. possibly if you make several short runs and with dampers heat one at a time it could be managed.

The better way to heat the ground which also works in the summer is to use the pipe in the ground and bring the chimney back inside the greenhouse to draw the hot air from the peak of the greenhouse  with a fan pulling the air up from the underground pipe.  This will heat he ground from your rocket stove in the winter and store heat from the sun all summer so the ground is warm in the winter  The plastic pipe will work for this but you may want to drill  some drain holes because water will condense in the pipes.  This will also happen trying to heat the ground with fire exhaust which has even more water in it.

My friend has a regular rocket mass bench above ground to warm the flats of seed starts. Our weather here is much like in Germany so we can start seeds of some plants under cover in January if the soil is warm.
 
Satamax Antone
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Michael Baer wrote:
Satamax Antone wrote:Michael, don't use those pipes. 65c° nowhere near good.


Well, I've understood.
But what are the alternatives?


Cheapest usually, hvac pipes (air conditioning or ventilation pipes)
 
Michael Baer
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Peter van den Berg wrote:Hi Michael,
The color of the buried pipe I find a bit suspicious. To my eye, it is the same as the PVC pipe for sewers here in Western Europe. So, just to be sure, that pipe should be metal otherwise you can't expect heat transfer from the pipe to the surrounding soil. Let alone the risk of melting or burning of that pipe.

Another possible snag: in the third picture the vertical exhaust diameter seems to be quite a bit smaller than the rest of the pipes and heater core. You definitely need a proper vertical exhaust pipe, reaching at least above the greenhouse roof and any higher objects in the direct vicinity.

I'll second Glenn's remarks, nearly every aspect of your design is out of the known configurations. When you want to build something that is quanteed to work, stick to the documented and tried solutions. Please note Glenn is talking about 30 to 40 feet, as opposed to 30 to 40 meter, which is 3.3 times as long as feet.



Hi Peter,
I have 2 questions at the moment. The length of the riser is measured from the bottom of the combustion chamber ?!
The additional air (secondary) should always be fed into the combustion chamber in front of the port. Not in the riser.
Greeting Michael
 
Peter van den Berg
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Yes and yes. Just like it's described at the http://batchrocket.eu/en/ site.
The next most common mistake is making the transition from the barrel to the rest of the heat extractor too narrow. Please, build this as wide and spaciously as you possible can, it will spare you a lot of headaches.
 
Michael Baer
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Hans Quistorff wrote:2 suggestions: There is a limit as to how much heat can be extracted from the the flue gasses.  They tried heating the ground in the underground house and it did not work the same as yours. possibly if you make several short runs and with dampers heat one at a time it could be managed.

The better way to heat the ground which also works in the summer is to use the pipe in the ground and bring the chimney back inside the greenhouse to draw the hot air from the peak of the greenhouse  with a fan pulling the air up from the underground pipe.  This will heat he ground from your rocket stove in the winter and store heat from the sun all summer so the ground is warm in the winter  The plastic pipe will work for this but you may want to drill  some drain holes because water will condense in the pipes.  This will also happen trying to heat the ground with fire exhaust which has even more water in it.

My friend has a regular rocket mass bench above ground to warm the flats of seed starts. Our weather here is much like in Germany so we can start seeds of some plants under cover in January if the soil is warm.



Hello Hans,
I have also thought of sending the warm air of the house via 12 V PC fan through the plastic pipes. These pipes are most cost-effective. The energy for the fan will be generated by a thermoelectric generator. This is when the oven burns a battery as well as feed the fan. The battery should serve as a buffer. And for the time when the stove does not burn.
The fan is controlled via a temperature difference module. The visualization is then done in my home control. Now I have but still work to optimize the furnace.
Greeting Michael
 
Michael Baer
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Peter van den Berg wrote:Yes and yes. Just like it's described at the http://batchrocket.eu/en/ site.
The next most common mistake is making the transition from the barrel to the rest of the heat extractor too narrow. Please, build this as wide and spaciously as you possible can, it will spare you a lot of headaches.


Thank you Peter.
I have understood that when secondary air is drawn into the riser, the air in the riser is cooled and is the counterproductive for the post-combustion in the riser.
That is, in my furnace is the tube in the middle that sucks the air from below a bad solution. The same applies to the secondary air supply at the right side of the combustion chamber.
Have I interpreted the right ??
Greeting Michael
 
Peter van den Berg
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The reason why secundary air is added just before or even in the port is because pressure is lowest, and gas velocity is highest. Air will be sucked in at that spot most efficiently, violent turbulence just behind will cause adequate mixing of the combustible gases and fresh air. When you feed air in at a later stage this isn't mixed that well. To find out all this costs me the best part of a year, and I tried literally every configuration I could think of, including something similar to yours.

So the answer to your interpretation is, broadly speaking, yes. Feeding in air at high temperature (commonly 350º C or there about, being the self-combustion level of woodgas) is also very important, nicely done by p-channel or floor channel alike.
 
gelu lacusta
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Burra Maluca wrote:On your picture, it says 5000 and 3500.

Does that mean 5 metres and 3.5 metres?

If so, I think there is too much pipe.  The stove won't be able to push the hot gas all the way through that much pipe, especially with all those corners.

What is the diameter of the feed tube and heat riser on the stove?  The greater the diameter, the further it can push, but I think you will still need to reduce the length of the pipes.
Ist-Zustand.jpg
[Thumbnail for Ist-Zustand.jpg]
fortare evacuare gaze arse
 
Michael Baer
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Peter van den Berg wrote:The reason why secundary air is added just before or even in the port is because pressure is lowest, and gas velocity is highest. Air will be sucked in at that spot most efficiently, violent turbulence just behind will cause adequate mixing of the combustible gases and fresh air. When you feed air in at a later stage this isn't mixed that well. To find out all this costs me the best part of a year, and I tried literally every configuration I could think of, including something similar to yours.

So the answer to your interpretation is, broadly speaking, yes. Feeding in air at high temperature (commonly 350º C or there about, being the self-combustion level of woodgas) is also very important, nicely done by p-channel or floor channel alike.


Hi Peter,
Thanks for your answer. The theme is always more interesting to me. Slowly I get behind the connections. It raises another question for me. As intended in the drawing, I intend to direct the combustion air through a DN 160 mm pipe into the walled wreath.
Is this ok or should the greenhouse be used for combustion.
Greeting Michael
Verbrennungsluft-Zuf-hrung.jpg
[Thumbnail for Verbrennungsluft-Zuf-hrung.jpg]
 
Michael Baer
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gelu lacusta wrote:
Burra Maluca wrote:On your picture, it says 5000 and 3500.

Does that mean 5 metres and 3.5 metres?

If so, I think there is too much pipe.  The stove won't be able to push the hot gas all the way through that much pipe, especially with all those corners.

What is the diameter of the feed tube and heat riser on the stove?  The greater the diameter, the further it can push, but I think you will still need to reduce the length of the pipes.



Hello,
Thank you for your project support
Best regards
Michael

I just saw the comment cooler, was overlooked in the first answer. What do you mean by that. If I would reinduct air through a fan, the exhaust gases are cooled down.
But what happens with the combustion in the box. Burns the wood faster? There is a vacuum.
Greeting Michael
 
Michael Baer
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Satamax Antone wrote:
Michael Baer wrote:
Satamax Antone wrote:Michael, don't use those pipes. 65c° nowhere near good.


Well, I've understood.
But what are the alternatives?


Cheapest usually, hvac pipes (air conditioning or ventilation pipes)


Hello,
Had your message almost overlooked.
These pipes are cost-intensive for this project. Even the m - price is high and the delivery costs would come. This is in no relation to the benefit.
Greeting Michael
 
Peter van den Berg
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Michael Baer wrote:As intended in the drawing, I intend to direct the combustion air through a DN 160 mm pipe into the walled wreath.
Is this ok or should the greenhouse be used for combustion.

Please don't connect an outside air feed directly to the combustion core, you'll run into problems with the air distribution between primary and secundary air like that. I would prefer to use the air inside the greenhouse. That greenhouse is leaky as it is, it isn't a passive house, isn't it?
 
Michael Baer
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Peter van den Berg wrote:
Michael Baer wrote:As intended in the drawing, I intend to direct the combustion air through a DN 160 mm pipe into the walled wreath.
Is this ok or should the greenhouse be used for combustion.

Please don't connect an outside air feed directly to the combustion core, you'll run into problems with the air distribution between primary and secundary air like that. I would prefer to use the air inside the greenhouse. That greenhouse is leaky as it is, it isn't a passive house, isn't it?


Thanks for the advice. I will follow. Until the next question.
Have a nice evening
Michael
 
Pascal Paoli
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Hi Michael,
falls du etwas übersetzt brauchst, schreib es hier rein. Der Luftzug wird z. B. nicht mit "train" (wie zug) sondern mit "draft" übersetzt. Das sollte dir vielleicht weiterhelfen. Updraft ist z.B Luftzug nach oben.


(If you need something translated into english from german, let me know. "train" is not "train" but draft, it's just the same word in german "zug".)
 
Michael Baer
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Pascal Paoli wrote:Hi Michael,
falls du etwas übersetzt brauchst, schreib es hier rein. Der Luftzug wird z. B. nicht mit "train" (wie zug) sondern mit "draft" übersetzt. Das sollte dir vielleicht weiterhelfen. Updraft ist z.B Luftzug nach oben.






Hello Pascal,
Thanks for your offer. And here at once a feast; How is batch box or batch box rocket stove translated. Rocket Stove is the rocket furnace or?
Greeting Michael
 
martyn parish
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Hi Micheal
I would like to add something to all the good advice on this this thread. I have built three rocket stoves and hope I can help a little.

The volume of each part of the stove is the critical factor. Each section of the construction should hold more volume of air than the last, if not you get poor air flow. It looks like the space above your internal chimeney riser between the enclosing drum/lid/barrel is too small. I would suggest either raising the drum, or shortening the riser. I had exactly this problem with my first rocket. The next ratio is the side space between the drum and the internal chimney riser. I use an 18 cm riser and 68 cm old oil barrels. This gives lots of space for the air at the top to fall to the exit pipe.
I agree with other comments about the exit pipe, it is too small in diameter. I estimate that with your current rocket dimensions your exit pipe must be at least 30 cm, but also the length of the pipe is too much and has too many angle bends. For best effect have a maximum of two angle bends. After each angle increase pipe diameter by about 20%. The pipe should be metal or ceramic. Not plastic or anything with a heat compustion temperature less than 200 degrees celcius!! Otherwise it can be very dangerous.
You could have the exit pipe not fully horizontal but at a few degrees angled up to encourage air flow in the right direction. Consider a 12 volt fan at the final outlet of the pipe. With these considerations you should be able to maximise the length of pipe in the ground, but it will require experimentation to see how much length you can have in this setup. I suggest buildling the rocket itself first without the exit chimney, test and get it burning well before adding the chimney pipes piece by piece to find the limits of your system. The performance will depend on some critical factors: ambient temperature and humidity, internal temperature and humidity (a rocket already warm inside will light much faster than a cold one, so the first time you light it is normally the most difficult), also the airflow into the greenhouse must be sufficient to keep the fire alight. An external cold air inlet tube is a good idea I think.
It takes some time to understand these little miracles and it it working, but it's well worth it! So have fun my friend!
If you have any further questions I am happy to help

 
Michael Baer
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martyn parish wrote:Hi Micheal
I would like to add something to all the good advice on this this thread. I have built three rocket stoves and hope I can help a little.

The volume of each part of the stove is the critical factor. Each section of the construction should hold more volume of air than the last, if not you get poor air flow. It looks like the space above your internal chimeney riser between the enclosing drum/lid/barrel is too small. I would suggest either raising the drum, or shortening the riser. I had exactly this problem with my first rocket. The next ratio is the side space between the drum and the internal chimney riser. I use an 18 cm riser and 68 cm old oil barrels. This gives lots of space for the air at the top to fall to the exit pipe.
I agree with other comments about the exit pipe, it is too small in diameter. I estimate that with your current rocket dimensions your exit pipe must be at least 30 cm, but also the length of the pipe is too much and has too many angle bends. For best effect have a maximum of two angle bends. After each angle increase pipe diameter by about 20%. The pipe should be metal or ceramic. Not plastic or anything with a heat compustion temperature less than 200 degrees celcius!! Otherwise it can be very dangerous.
You could have the exit pipe not fully horizontal but at a few degrees angled up to encourage air flow in the right direction. Consider a 12 volt fan at the final outlet of the pipe. With these considerations you should be able to maximise the length of pipe in the ground, but it will require experimentation to see how much length you can have in this setup. I suggest buildling the rocket itself first without the exit chimney, test and get it burning well before adding the chimney pipes piece by piece to find the limits of your system. The performance will depend on some critical factors: ambient temperature and humidity, internal temperature and humidity (a rocket already warm inside will light much faster than a cold one, so the first time you light it is normally the most difficult), also the airflow into the greenhouse must be sufficient to keep the fire alight. An external cold air inlet tube is a good idea I think.
It takes some time to understand these little miracles and it it working, but it's well worth it! So have fun my friend!
If you have any further questions I am happy to help



Hello Martyn,
Thank you very much for your critical comments regarding my design. As I said I had not found any information that helped me in questions of the dimension. Now it looks different thanks to this forum. Also, there are many forians who try to help me.
At the moment I am still on vacation and I use the time as much as possible ask questions and collect information. What is certain for me, however, is that I remove the entire inner metal structure and realize the inner life with shamotine stones. The outer cover of the container sol remain. I am considering a 4 "or 5"
Furnace to build. If the smoke outlet is 6.3 "sufficient for this size.
Greeting Michael
 
Michael Baer
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Peter van den Berg wrote:
Michael Baer wrote:As intended in the drawing, I intend to direct the combustion air through a DN 160 mm pipe into the walled wreath.
Is this ok or should the greenhouse be used for combustion.

Please don't connect an outside air feed directly to the combustion core, you'll run into problems with the air distribution between primary and secundary air like that. I would prefer to use the air inside the greenhouse. That greenhouse is leaky as it is, it isn't a passive house, isn't it?


Hi Peter,
I have two more questions that seem important to me. There are <BR> burner (batch box) and <J> burner Rochet Stove. If I correctly understood the RS burns very slowly How is the combustion speed with the BB. I could imagine that because of the large combustion chamber a faster combustion takes place.
Since I would like to use the container further. Is the next consideration interior life 4 "or 5" from fire stone.
If a stone strength of 1.18 "is sufficient or if stronger material is used.
Is the existing flue gas output sufficient for 4 or 5 "?
Best regards
Michael
 
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