Rocket Stove for heating home...

[therunbunch]

Does anyone have anything like this that you built?

http://www.iwilltry.org/b/build-a-ro...-home-heating/

We've been looking into it.

[meanwhile]

Oh my! That looks so totally dangerous. I would be scared of it but....having said that....the most dangerous Wood Stove I ever saw was built by an elderly neighbor couple. They used an old metal barrel, set it up on legs, cut a door in it and piped it out with metal stove pipes. It is the only heat in their house and they have heated this way for over 40 years......it was a very scary looking Stove......but it worked!

Good luck!

[Nevada]

I don't know how dangerous it might be, but it seems like it would be a lot of trouble to keep fuel in it.

[therunbunch]

It's a very low fume and "fuel" system. Basically it works using twigs.. and not much of them due to the designs. We've heard from many people that it's an extraordinary way to heat a space. We're going to built a more conventional (small) "rocket stove" for cooking outdoors when the power goes out. It provides more flexibility and we have good stores of wood and twigs for that purpose. Scary is a good word for it as first glance, lol.. that's exactly what I said when I first saw it. But after reading up on many "models" and techniques.. I'm game for a trial run. Just wondering if anyone had used this particular method.

[Helena]

Many years ago I remember a family that had what looked like to me an tall skinny hot water tank with an opening on the bottom that you put small sticks of wood into it to burn and heat the water. They were pleased with it and it was fast to heat the water. Wish I had taken more notice of it at that time . the comment about the barrel stove on legs that the elderly couple heated their house with..well..we have one we made also in our cellar that works wonderfully. If I had to have one stove to heat and even cook on top with..it would be a homemade barrel stove. Completely safe when used with common sense as using any wood stove.Been using it for over 30 years now..

[Immaculate Sublimity]

There have been several posts here regarding rocket stoves. Do a search.

[frank]

I've built a few rocket stoves and will share my opinion of this one. The only thing I don't like is the exhaust system. I would prefer to vent the exhaust from the unit straight out a wall (sideways) to the exterior of the building. The unit itself looks like it will work very well. I don't like the idea of trying to vent gasses out of the structure in a fireplace chimney because the gasses are not very hot, and co2 tends to settle(sink in relation to ambient air). Also, the exhaust could be covered with thermal mass as it exits the structure to hold more heat( I've used cobb and concrete previously with good results...like a cobb bench.

Pros: 1. light weight as opposed to building one with firebricks ( but you lose the thermal mass )
2. (portable)

good luck!

[Yvonne's hubby]

The problem I see is not with the stove.. but using an aluminum dryer vent pipe is just asking for trouble. Creosote burns pretty hot, enough to melt that aluminum.

[therunbunch]

Originally Posted by frank

I've built a few rocket stoves and will share my opinion of this one. The only thing I don't like is the exhaust system. I would prefer to vent the exhaust from the unit straight out a wall (sideways) to the exterior of the building. The unit itself looks like it will work very well. I don't like the idea of trying to vent gasses out of the structure in a fireplace chimney because the gasses are not very hot, and co2 tends to settle(sink in relation to ambient air). Also, the exhaust could be covered with thermal mass as it exits the structure to hold more heat( I've used cobb and concrete previously with good results...like a cobb bench.

Pros: 1. light weight as opposed to building one with firebricks ( but you lose the thermal mass )
2. (portable)

good luck!

Thanks for your insight!

[Ed Norman]

We bought this place from an old man who died before I met him. He made these funny little stoves, there are several around here. I have no idea how to use them and what they are even called, so I haven't been able to search for them. Never tried lighting one because I wasn't sure where the fire goes and where the fuel goes, and I think he might have burned sawdust or chips but that is a guess.

They are around 3 feet tall, the upright is stovepipe about 8" diameter, then an angled pipe about 4" sloped from the base and outward so it is a foot away from the big pipe at the top. There are lots of little pieces made from tin cans, he really seemed to enjoy tin can work.

[SolarGary]

Originally Posted by frank

I've built a few rocket stoves and will share my opinion of this one. The only thing I don't like is the exhaust system. I would prefer to vent the exhaust from the unit straight out a wall (sideways) to the exterior of the building. The unit itself looks like it will work very well. I don't like the idea of trying to vent gasses out of the structure in a fireplace chimney because the gasses are not very hot, and co2 tends to settle(sink in relation to ambient air). Also, the exhaust could be covered with thermal mass as it exits the structure to hold more heat( I've used cobb and concrete previously with good results...like a cobb bench.

Pros: 1. light weight as opposed to building one with firebricks ( but you lose the thermal mass )
2. (portable)

good luck!

I'd like to heat my shop with something like this -- I think I generate enough scrap that this thing plus the solar heater should do the whole job.

The only practical way I have to vent the fumes is out the side wall, and I would basically have to terminate the vent very near where it goes through the wall. That is, I can't run a vertical vent pipe up the wall to some point above the roof.
Based on your experience with rocket stoves, does this seem doable? safe? won't make smoke stains all over the side of the house?

Gary

[mduncn52]

Paul Wheatons, Permies site has a lot of Rocket stove info

[||Downhome||]

Originally Posted by Yvonne's hubby

The problem I see is not with the stove.. but using an aluminum dryer vent pipe is just asking for trouble. Creosote burns pretty hot, enough to melt that aluminum.

Rocket stoves are not your conventional wood burner.

there are different designs, the ones used for heating should have complete combustion.

You have a primary combustion in the chamber and secondary combustion in the next chamber prior to being exhausted.

So a properly designed unit there would be no creosote.

Most are designed with thermal mass to make full use of the heat.
they exhaust to the side rater then up because as Frank noted the flue Gas is "cold".

You have Draft from the combustion to the secondary,then the gas is pushed
by that. Cooling as it passes around in the thermal mass.

I don't really see that Unit having to cool of a flue gas though. But its can't be hot enough to rise in a large cold chimney.

[SillyMe]

Hi therunbunch. Have you ever used a rocket stove? There are only two ways that I can think of to possibly heat a room with one.

One - route the flue gasses through a thermal mass such as rocks, sand, liquid, cob, concrete, etc. Fire the stove for several hours while feeding little sticks into the burn chamber. This will raise the temperature of the mass and this mass will slowly release the warmth into the room long after you allow the rocket stove to cool. A rocket stove requires constant effort to feed the fuel.

Two - stand there all day and night feeding little sticks into the burn chamber.

I have two rocket stoves. One is used in the early spring/late winter to process maple syrup. And the other is used to provide an outdoor cooking area when the grand kids are camping in out back yard. Both require continuous tending of the fire with sticks. It's great fun for the kids but not practical at all for heating a home. Just my opinion.

[AR Aaron]

Originally Posted by therunbunch

Does anyone have anything like this that you built?

http://www.iwilltry.org/b/build-a-ro...-home-heating/

We've been looking into it.

I have been interested in the Rocket Stove Thermal Mass stove/heaters for a while. Been trying to figure a way to incorporate one into current house and this looks pretty interesting.

[Common Tator]

I hadn't checked this thread, because I assumed you were talking about the rocket mass heater that Paul Wheaton has posted about. Then I looked at your link, and the guy who posted it got the beginnings of a rocket mass heater, but forgot the mass. Look at some of the you tubes by Paul Wheaton, at permies.com. Here is one of them, where the mass is a sand filled bench. The mass absrbs the heat from the rocket heater, and releases it over a period of hours. And it is far safer than the cardboard firetrap the guy in your link uses.

http://www.youtube.com/watch?NR=1&v=2bsUd5zLcLw

Edited to add: look at he rocket mass heater here: http://www.jocelynsevents.com/rocketstove/ it is beautiful. This cobb built in bench has the duct work running through it. They make a small fire in the rocket stove, and the heat goes all through the ductwork in the bench. That is their heat sink, and it releases heat for hours.

Here is another of Paul Wheaton's videos showing 12 rocket mass heaters.

YouTube

I want to be clear. I haven't built one of these. I have been toying with the idea of doing this in a greenhouse. Paul Wheaton is a member here. You might want to contact him to see if he has built one. I don't know how often he checks in here. You might want to contact him through www.permies.com

[||Downhome||]

this is a cool design, may give you folks something to think of.

http://www.ovenwerks.net/family/2011/RMH/index.html

its loosely based on Paul's "portable" sand bench.

Both are great concepts.

The Mass in a traditional design is normally cob. Not such a great thing for a conventional house. but both of those concepts stem that some what. though I dont really want a bunch of sand in the house.

I may Build one for the shop.

I think I will make it with a larger feed then standard design. for one it would help with the Firing in two ways. the feed stock could be larger, less work breaking large stock down. with more fuel per firing less tending.

[DanielY]

I am building tearing down and rebuilding a test rocket mass heater in my back yard. we plan to build one on our patio for now. We have not yet decided if we will build one inside.

I finally bought the book and have found several things wrong with our attempts so far. They are very easy and cheap to build but they have to be built right. I can't say much about the design in the OP simply not enough info. I don't like the duct work. Our stove will still be about 700 degrees at the point that one have the dryer vent connected. You do have to worry about holes getting in that vent. there are dangerous gases that can escape to your living space.

I know our stove burns with no smoke in less than 3 feet from the burn box. Very hot fire means less bad things in teh exhaust and so far our tests show this stove burns very clean.

I have not found the fire needs to be constantly tended. We can spend maybe 30 minutes leading twigs and getting a good bed of coals going then they will glow for about 2 to 3 hours. we can then reload the burn box if needed. A 3 hour burn makes a ton of heat though.

The burn box is one of the hardest parts to design. First the post above showing stove pipe as the burn box and heat tunnel is wrong. You want the box and tunnel to be square with right angles to the corners. In the burn tunnel you want the air to get stirred. then you go to round duct for the rest of the system to let the air flow without obstruction. Otherwise the burn box needs to be small. This in combination with the heat riser being taller will create more draft. more draft in the burn box results in a fire that stays down in the bottom of the box preventing smoke back or the fire climbing up the pieces of wood and out of the box. This is the number one problem we have been having so far. if we drop long sticks into the burn box the entire stick wants to catch on fire. Better draft is the answer. I will have to update as we improve on this problem.

As for burning twigs. This is not a problem. this stove requires very little wood in the first place. Some claims say that a house that uses 4 cords of wood per year can reduce that to 1.5 cords. Fairly convincing measurement since this was observed in two separate houses at the same time using to different wood burning methods.

I can say that when built right and burning hot these stoves produce no smoke even after traveling just a few feet through the burn box and heat riser.

I will also say they produce a lot of water. steam from the exhaust will condense on the duct work run down and collect in pools. Whatever your design you need to be able to get this water out of the duct work. I woudl suggest your duct work be layed out to constantly slope back tot he ash clean out. I am still toying with this problem as well.

We started with a 6 inch heat riser, 30 gallon barrel and 6 inch duct. but we are now going to make a new one with 8 inch pipes and a 55 gallon barrel. To many reasons for this to go into here. in short it makes a stove with the heating ability almost twice that of the smaller one.

You can alter your design to get faster more immediate heat from the barrel or slower longing lasting heat from the mass. in fact you can cover the entire stove in cobb and have nothing but a mass heater.

I highly recommend you build one outside that can be put together torn apart and try something new. once you have it exactly the way you want it. you can build it in the permanent location. The cobb is nearly free, we make it from the dirt in our back yard. it is reusable as well. All we have to buy is the sand and straw. We are not adding straw to our cobb yet as we don't intend to keep the stove where it is.

If you look at the history of the person that designed this heater you will find he is not playing around. people in other countries are living by this design. The concept is very young so not real popular. and the design is not perfected. their book even lists details that still need research done on them. Just be aware of what you are looking at here. it has not been tested and proven for centuries like other methods have. You are not going to go out and slap one together and nobody next door is going to be able to help you figure out the problems. The book has a design that is known to work. they suggest you start with it and then experiment from that. After starting on our own I also recommend you start with a proven design and then try to alter that to suit yourself. very small changes can impact the performance severely.

[therunbunch]

Thank you for all the information and thoughts!! I will be checking out (rather redirecting DH) to Paul's site to see what he thinks would be best. Our neighbor has 2 hot water heaters he is giving us.. so that is a huge plus if we could use them.
I'm always impressed at how many knowledgeable people are here on HT. Every time we start a new project or try to learn something new, there are always so many helpful folks around to give their two cents. Much appreciated!!!

[Astrid]

We are building a rocket mass heater which is taking the rocket stove and piping the smoke through a pipe surrounded by cob. It burns very cleanly and works a lot like a Russian masonry stove without the enormous bulk.