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7 gallon pocket rocket barrel heater  RSS feed

 
Chris Burge
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built this in about an hour with parts left over from the last project. 6in feed, 5in chimney. Burns hot and clean.
 
Chris Burge
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here are a few photos of the construction








 
allen lumley
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Chris Burge : Two thumbs up! Great, can you verbalize how you did your rollover crimping!?

Knowing that the combustion air supply would greatly expand with the freaky hot temps, did you Plan on a smaller exhaust pipe to 'slow the flow' of the exhaust gases ?
The more i think on it the more I like it ! For the craft, BIG AL
 
R Scott
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allen lumley wrote:Knowing that the combustion air supply would greatly expand with the freaky hot temps, did you Plan on a smaller exhaust pipe to 'slow the flow' of the exhaust gases ?
The more i think on it the more I like it ! For the craft, BIG AL


The wood in the feedtube restricts the air intake enough to balance it out. All the designs I have seed use one size bigger for the feedtube than the exhaust. Once you get the hang of it, you can slow the burn by over-feeding it and restricting the air SLIGHTLY. But for the most part a pocket rocket usually has 2 speeds, ON or OFF.
 
Chris Burge
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Thanks Al.

I did the roll-over crimp with a hammer and a pair of channel-locks...tap tap tap, crimp crimp crimp, done!

The reasoning behind the smaller chimney is 1) it's what I had on hand; 2) I built another one of these back in March, but a 6in chimney-- I didn't like small gap between the two holes in the lid... This version is a but more sturdy; 3) when burning, the CSA of the feed tube is greatly reduced due to the presence of the fuel.
 
Tom OHern
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I love it!

What is the clearance between the bottom of the barrel and the bottom of the feed tube?

Does the wood rest directly on the bottom of the barrel?

And if so, do you put any firebrick below the feed tube to prevent the fire from burning out the bottom of the barrel?
 
R Scott
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A firebrick is good, sand or cob work too. Distance needs to be roughly equal to twice the CSA (area of the cylinder vs. area of the circle) because the tube is right beside the barrel and it doesn't flow evenly the whole way around.
 
R Scott
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http://www.rocketstoves.com/pdf/pocketrocket.pdf

An excerpt from the rocketstove book explaining them. As Ianto says, all the dimensions are fudge-able. They are open to interpretation.

And the link mentioned in the podcast w/ Jack last week with the GLOWING barrel: http://canadiandirtbags.wordpress.com/2010/12/05/how-to-build-a-pocket-rocket/

 
Sean Kibler
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Not sure I'm comprehending what proportional means in Ianto's excerpt from the pocket rocket PDF http://www.rocketstoves.com/pdf/pocketrocket.pdf

It says in a 5-gallon 4x60" flue with 6x12" feed works well, and in a 25-gallon 4x66" flue with 8x25" feed works well.

So I'm making a 55-gallon could I just use the same pipe sizes as the 25-gallon. According to [http://en.wikipedia.org/wiki/Drum_(container)#Background] the 25 and 55-gallon drums are the same height, so the 25" feed would extend the same distance from the bottom of the barrel as it does in the 25-gallon.

I know that RMH for sure are very sensitive when it comes to CSA, does the same apply to pocket rockets?

I'm generally just confused on what part is "fudgable".
 
allen lumley
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Sean Kibler : Trust but verify : Barrels were standardized for the war effort, nothing is truly standardized, many people find that they can make work what they have got,
even pinching the pipes 'out of round' into ovals to fit on the lid! Then you can regulate your air flow with the amount of wood that you feed it, or a brick, or a tea kettle,
have fun experimenting and post some pictures ! Big Al
 
Sean Kibler
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I want to go with a 6" flue at 60" - 66" right?
 
allen lumley
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Yup, that will definitely work, loved by preppers, zombi hunters ice fishers,and People on picket lines (here it can set fire to blacktop and spall
wet concrete !Big AL !
 
Chris Burge
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Tom: The gap at the bottom of the feed tube is 2" and, yes, the wood rests directly on the bottom.

Al: I've found it's best to put these on top of three fire bricks to help prevent asphalt combustion
 
Chris Burge
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Just made a pellet feeder for the pocket rocket!
 
jacob green
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Chris Burge wrote:Just made a pellet feeder for the pocket rocket!


Cool.

How does the bottom of the pellet feeder work? What keeps the pellet feeder from becoming a chimney? What kind of barrel is that and where did you get it?

Also, with or without pellet feeder, how long would one expect a system like this to last before the metal falls apart?

Could such a system be improved by insulating the air path, also increasing longevity of the metal?

If burn tunnel and riser were insulated, would this system compete in efficiency with a well built RMH? What if it was insulated AND added a barrel around heat riser.

I am interested in this shape mainly because it holds WAY more wood than conventional rmh. Resuting in less tending. Especially if you can use pellets to feed it.
 
Chris Burge
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Jacob,

Thanks.

The feeder is just a couple of pieces of 3in exhaust pipe-- an 18in straight piece and a bent slant tip. I made a couple of cuts on the end of the tip and bent the center piece into a crude peg shape.

The bottom of the pellet feeder is an iron trivet with three 1in bolts as legs.

The peg rests in one of the holes in the trivet. The edge of the feed tube helps control the flow of pellets.
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The stove's outstanding draw prevents the feeder from backdrafting.

The barrel is a 7 gallon steel heavy gauge with a ring clamp lid. I picked it up at a local salvage yard.

I'm about to experiment with insulating the feed tube on this one-- I've got some ceramic wool and S/S band clamps that should do the trick. With the pellet feeder, it's not an issue, but when I burn it with just wood, the tremendous heat ignites all of the fuel in the feed tube all at once and causes the system choke itself down with embers.

I haven't used a stove like this for an extended period of time, and this one is only a couple of months old, but I know that the stovepipe doesn't hold up very well at the bottom edge of the feed tube where temps are highest. The barrel, however, is far more durable. Using the pellet feeder exclusively would make a system such as this last much longer-- the feeder setup keeps the fire in the center of the barrel and maintains a consistent burn rate. Although it remains to be seen, I suspect that the feed tube will hold up a bit longer when insulated.

This little stove just has a chimney, not a heat riser, and insulating it would defeat the purpose since a lot of radiant heat is emitted from the chimney itself.

I would not consider ones of these stoves to be as efficient or hold more wood than a "conventional" RMH, but they do produce high enough temps to result in a very clean burn.


Check out this thread to see the small format RMH I built that includes a pellet feeder.

http://www.permies.com/t/22486/rocket-stoves/mini-rocket-mass-heater
 
jacob green
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Wow. REALLY cool. That link to indoor RMH is exactly how I am trying to set up my friends hearth/unused fireplace. On the indoor RMH, how long does that stack of pellets burn for?

Back to the 7 gallon stove....

Chris Burge wrote:
This little stove just has a chimney, not a heat riser, and insulating it would defeat the purpose since a lot of radiant heat is emitted from the chimney itself.


I was thinking that one could put an external barrel over the riser to essentially trap more heat because the exhaust gasses would ultimately be cooler because more heat had slowed down for radiating to the persons standing around the barrel/bell.


Chris Burge wrote:
I would not consider ones of these stoves to be as efficient or hold more wood than a "conventional" RMH, but they do produce high enough temps to result in a very clean burn.


I could see where you would say it is not as efficient because the proportions/draw etc of existing RMH design is already close to perfect. But it doesn't hold more wood?

How long is the effective length of the feeder tube? It looks to be at least twice as long as the feed tube on any standard j tube. Am I looking at it wrong? How could more/longer wood not fit in to a longer tube?
 
allen lumley
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jacob green : This is a lovely project to experiment and play around with out doors, many local ice fishers set up wind breaks and use 5-7 gallon pails to make
Pocket Rockets ! You get to hear the rockets roar, and is part of the mandatory equipment for Preppers and Zombie Hunters, your ferns will think its cool and
you can use it Tailgating !

It Can set fire to black top and cause damp concrete to chip and spall, and sends most of its heat up the chimney ! Because there is Zero Heat energy storage
compared to the rocket mass heater, The air that it warmed seconds ago immediately becomes combustion air. When you have burned through your wood
supply -(It goes thru a lot of wood ) Everything cools down very fast ! For the good of the Crafts !
 
Rusty Humperdink
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I am interested in building a similarly sized (7 gal) pocket rocket, but the tubing that I have for the chimney is about 3' long (Ianto recommends 5'), and the tubing that I have for the feed tube is about 8" long (Ianto recommends 1'). Is it resonable to try putting one together with what I have, or should I wait until I can get longer tubing? What differences would there be in how the heater works given the different length tubing?
 
allen lumley
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Rusty Humperdink : You are going to have trouble getting it to start to Draw actually more so on warmer days than on the colder days with more difference in the
temperature between the fire and the Air. To use it as is -until you have better pipe put about 3'' of sand in the bottom, and stuff the bottom well with news paper
that has been hand shredded into long thin ribbons of paper to fill the bottom, always prepare and use the smallest, very dry wood, split thin, after 60 seconds of
burning you should hear the Throaty Purr of the Dragon that lives inside every rocket. and see almost no visible smoke ! Good luck and welcome to the ranks of
your fellow rocketeers ! Big AL
 
Rusty Humperdink
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Thanks Al! Is there a temperature differential between the air and a particular part of the heater that creates the draw? Why will putting sand at the bottom of the barrel improve the draw?
 
allen lumley
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Rusty Ianto Evans gave you the proper length of pipe to have a proper gap at the bottom, This is a ''if you can't lower the water, raise the bridge''

way to give you that proper gap ! Also if you have a two identical funnels except one has a longer spout on it the one with the longer spout will

draw best, Its the difference that makes them draw, as soon as the final vertical chimney gets warm it will 'draw' like crazy ! Big AL
 
Rusty Humperdink
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Got it! Thanks!
 
allen lumley
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Rusty : Right after I posted to/with you I went out, found my last 5 gal pocket rocket, and said what the hell, I didn't want the kill any grass so I set it up on the blacktop,
and lit it up just to see how long it would smoke before settling down with an outside air temp of 40ºF .

I was burning up some lathe and garden stakes and some very dry sunflower stems, when my neighbor came over to be a Lookie-Lou and I was showing him that his
Cell Phone Camera would catch the bottom of the 5 gal pail glowing in the infrared before we would see anything and proceeded to melt the blacktop! We had to steal
some bricks from the border of my wife's flower garden, picking up corners of the pail with a shovel to raise it up off of the Black top !

At the end of the burn I worked on putting things back the way they were and parked the car to hide the new mark, and my neighbor went home with my Pocket Rocket
to hold as ransom until we get together to make more!

I'll help him make a pocket rocket or two, and when he comes home from a later ice fishing trip -i'll have a fish dinner ! Good on ME ! Big AL
 
Rusty Humperdink
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That's awesome!

BTW: I will be using conduit for my chimney. It has a grey coating of some kind on the inside that I am trying to remove. In Ianto's book he recommends burning the coating off of the materials, but I can't have a bonfire in my current situation, and I can only reach about a foot into the pipe with sandpaper. I suppose I could just build the heater and let the first use burn off the coating, but do you know of any other options?
 
allen lumley
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Rusty : All pocket rockets should be used outdoors only, a pocket rocket made from a 55 gal drum with the one end removable is a good way to burn the paint
off of the Inside and Outside of the drum! A pocket rocket can be a very good thing to have around, and by protecting the ground under the base you can even
use it for a patio heater and extend your outdoor season a little. If you have neighbors who will freak out when the paint burns off - - - well really you're on your
own. Not much help here Good luck any way! Big AL !
 
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