Rocket stove working!

[Ernest_T._Bass]

Ok, I don't want to get too excited yet, but we added 20' of vertical stack to our rocket stove and it has been running great with no smoke all for two days! We just used cheap galvanized pipe that probably won't last too long, but we just needed to see if the stack would solve our draw problem and get us through the winter. The draw has been great, even in 25 mph winds with no cap.

Just thought Glenn might be interested.. The draw is so good it can be scary at times.. Like there's no limit to how hot it can get. I'm afraid of busting the bricks I used to make the heat riser out of. If I were to build it again, I think I'd use a chunk of clay chimney tile instead.

We may post a video on our blog..

[glenn-k]

That is great, Andrew.  

It must be the wind currents and turbulence near the house with the short stack that cuts down the draw then.

[Ernest_T._Bass]

I guess... At times, now, the high winds actually increase the draw. Other times they slow it down temporarily. It seems that the tall stack sorta acts as a buffer that can ride out some wind turbulence without reversing the draw, whereas before the tiniest breeze in the wrong direction could send us gasping for the door. I've been impressed with how stable the draw is in spite of the wind, but we are considering getting the vacu-stack chimney cap just to be on the safe side.

Most of the time, there is no visible smoke leaving the chimney, even when the fire is blazing. (And that's burning crummy Aspen!) At cooler temps you can see a little white steam.

[glenn-k]

Weather conditions can greatly affect pressure at the ground and the closer you are to the ground the more pressure a good downdraft can exert on your stack trying to get in.  Winds are about triple what you see on the ground at 100 feet up, so likewise - pressure on the ground is more because the things making the turbulence and killing the wind are causing much more unstable conditions to do it.

Flying, I have seen steady downdrafts for over 100 miles.  The same things that affect the planes can affect your draft.  I really noticed the pressure changes from different direction winds on the draft with my shorter stack.  Just never did put a bunch of pipe to see what the changes would be.  Your experiment does make a lot of sense when you consider what is going on.  Good Job.

[Ernest_T._Bass]

Thanks! We're just so relieved that the countless hours, days, weeks, etc. that I've spent on this thing might pay off after all.

I'm wondering how long the galvanized vent pipe we used for the stack is gonna last.. I heard that the acidity of the exhaust moisture is what will do it in right away.. Could the rocket exhaust be any less acidic because of the clean(er) burn? Even if it just gets us through the winter, I'll be happy. The cheapest well casing we could come up with was 8 bucks a foot, and we weren't sure how to erect a 20' chunk without heavy machinery anyways..

[Homegrown_Tomatoes]

Will someone bring me up to speed?  What in the world is a rocket stove?  Do you have pictures of this contraption? :-?

[glenn-k]

A rocket stove is a stove designed to burn wood extremely efficiently and store the heat in a cob bench or other storage (adobe built in place -not from bricks but mud, composed of clay sand and straw )

Link here - my experimental one would last longer if it was fire brick rather than steel.

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1167119392

Andrew and family built a nice one.

I think there are photos in his family's project.

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1168453897/0

[Homegrown_Tomatoes]

Thanks for the links, Glenn...  rocket and stove were two words put together that had me a little worried before you set me straight.

[glenn-k]

My pleasure, Homegrown.  Just a cool name a bunch of hippies came up with I think.  

It can sound like a rocket when burning fiercely.

[jraabe]

Congrats to ETB!

There is probably more information here on the forums concerning these high power rocket stove experiments than anywhere else on the net.

Lots of interesting hands-on research. Always good to remember that [highlight]WE ARE PLAYING WITH FIRE[/highlight]. So be safe is the first rule.

[Ernest_T._Bass]

Yeah, you have to be careful... Playing with fire can be real addicting when it does what you want, though...   Still not one puff of smoke at all, not even when starting the fire. You can hold a smoldering log about a foot and a half over the flames and every bit of smoke gets sucked down. I think this thing has kinda turned me into a pyromaniac. 8-) I definitely plan on building more in the future if the stove pulls us through the winter..

[glenn-k]

Sounds good, Andrew.  Since mine was experimental and not as well planned as yours, I am going to pull it out.  The space I have it in doesn't really lend itself well to the layout with the rocket stove there...  But it was well worth doing.  We have a smaller bedroom stove and will move the Franklin heater from the bedroom to the great room.

I also, would use a firebrick burn tunnel after seeing how fast the steel oxidizes under the intense heat when it is working properly.