My sad attempt at a rocket stove heater

[woodman6666]

I work with steel alot so I thought I would try to build one of these out of steel I have been reading about them lately. This is what I threw together this afternoon, still have to put the insulated cement between the upright tubes and around the entire burn chamber, then have to put the outside barrell on which sits on the flange on exisitng tube. I made a kind of steel pallet of sorts so I could move it around with a skidloader. Plan on firing it on monday I will post back finished pics and some results, I have no idea how well it will work but kind of a fun easy project.

 

[dave_376]

looks good so far. I am thinking of making one as a pool heater. Either by wrapping copper pipe around the exhaust pipe with the insulation on the outside of that or making a water jacket instead of insulation and slowly circulating the pool water through it to heat it up. although I'm a little worried that the water may cool down the flue too much making it less efficient and not a really good pool heater.

 

[trailmaker]

That is friggin' awesome Woodman. Keep us posted on your progress, I've always been interested in those rocket stoves.

 

[Whitespider]

That's a lot of work... and a lot of steel for one afternoon.
It does look good. Interested in the test-fire results.


:msp_mad: I spent most of the day working on my wife's mini-van.

 

[imagineero]

You might have over engineered....

The classic rocket cooker/water heater is based around very thin metal, often made in an old olive oil tin or something similar with lots of insulation. To get your head around why they work with so little fuel requires a limited understanding of thermal mass vs. insulation. Thermal mass acts like a hot water bottle, insulation is like a doona. Thermal mass acts like a battery and can absorb and store a lot of energy. It works great when you have widely fluctuating day/night temperatures and lets you store the heat of the day to even out the night for example. Water, steel, rock, clay etc all act as good thermal mass and gain/lose heat at the rate of about an inch per hour in the dense areas.

Rocket heaters have no thermal mass. This means they take very little energy to get them rocketing. A handfull of twigs can boil a kettle. They gain their efficiency by not losing heat by having insulation, and windshields. As a boilermaker I'd say your sections are too thick. They act as sponges for heat until they are up to operating temperature, then they take a long time to cool down. Most of the energy from your fuel will be lost in getting the system up to operating temp, and there will be a long delay between lighting the fire and getting usable heat.

Nice welding though. A pot belly is really more suited to heavy construction.

Shaun

 

[trailmaker]

You might have over engineered....

The classic rocket cooker/water heater is based around very thin metal, often made in an old olive oil tin or something similar with lots of insulation. To get your head around why they work with so little fuel requires a limited understanding of thermal mass vs. insulation. Thermal mass acts like a hot water bottle, insulation is like a doona. Thermal mass acts like a battery and can absorb and store a lot of energy. It works great when you have widely fluctuating day/night temperatures and lets you store the heat of the day to even out the night for example. Water, steel, rock, clay etc all act as good thermal mass and gain/lose heat at the rate of about an inch per hour in the dense areas.

Rocket heaters have no thermal mass. This means they take very little energy to get them rocketing. A handfull of twigs can boil a kettle. They gain their efficiency by not losing heat by having insulation, and windshields. As a boilermaker I'd say your sections are too thick. They act as sponges for heat until they are up to operating temperature, then they take a long time to cool down. Most of the energy from your fuel will be lost in getting the system up to operating temp, and there will be a long delay between lighting the fire and getting usable heat.

Nice welding though. A pot belly is really more suited to heavy construction.

Shaun

It seems like he's not trying to build a classic rocket cooker, but a rocket mass heater. Rocket mass heater - Wikipedia, the free encyclopedia

 

[adunn21]

This is too cool. I was talking to my Czech buddy ( he was in CZ while it was Communist controlled) about a year ago about an idea I had about building a unit into the hill that is next to my basement to supplement the heat there. Back to CZ, hw was telling me about what I now think was a unit that is along the lines of the one you are building. Keep building that thing and good luck!

 

[PEKS]

Woodman,
That looks darn good, very productive afternoon..

 

[woodman6666]

Thanks guys! Imaginero your words are very encouraging to me as everything you see so far is designed to keep heat in. I have to add insulating cement between the two pipes and suround the entire burn tube all the way over to the air inlet, the steel on the sides is the forms for this. It is the last and outside barrell that you want thin and it is ready to be put on as soon as the cement is in. by the way the thickest steel on the whole project is 1/8" the larger upright tube is 12 gauge the camera may have made them look larger. It will get fired Monday it will be interestin to play with where it gets its air either from the feed tube where the fuel will stand or from the end of the pipe I will try this both ways, I would like to build the feed tube taller and cap it and run only with air from the tube but I have no idea what will work or not, interesting to try.

 

[fubar2]

Fire her up and get back to us with the results.

 

[old cookie]

Very nice work looks really good,but i have no idea how it works. Does it burn wood if so were do you put the wood i just cant get how it works .Really wont to see how it works once again nice job.

 

[woodman6666]

WEll fired it on Monday with goods and bads. The goods are my heat riser barrell the outside barrell when shot with temp gun achieved 500 degreesF while the chimney out the back was below 200 degreesF. The bad is the feed tube where the wood stands and falls whent the bottom is burned off gets way to hot it seems that 80% of the fire goes through the burn tube and up the heat riser as it is supposed to but about 20% of flames and heat want to wander up into the feed tube even when it is capped air tight. I will have to play with it some more here are a few pics of finished.

 

[Steve NW WI]

Woodman, it looks like you are getting your combustion air from the stove pipe on the end of the heater? From what I've seen on other sites (after seeing your idea here and researching a little more), they seem to be built to downdraft the intake air through the feed tube, which would solve your heating problem once it starts drafting. Not sure how to get the side draft started though.

Keep us posted, it's a neat little project. What are the plans for it if you get the bugs worked out?

 

[woodman6666]

Woodman, it looks like you are getting your combustion air from the stove pipe on the end of the heater? From what I've seen on other sites (after seeing your idea here and researching a little more), they seem to be built to downdraft the intake air through the feed tube, which would solve your heating problem once it starts drafting. Not sure how to get the side draft started though.

Keep us posted, it's a neat little project. What are the plans for it if you get the bugs worked out?

You are correct I was trying to see if I could connect the intake air to pull in from outside the building thru the end of the pipe. Since I have been in contact with the people who pretty much wrote the book on these things and I am going to try a couple other things.