a non rocket heater!

[toby916]

ok so after trying to heat myself for as little cost as possible i built a "mass heater without mass"

(just a note i plan on making everything in 6inch as soon as i can afford but the mass and bends will be the same

consisting of 3x3 box section
47kg gas bottle
5.5 inch ducting (flexible)
home made h cowl
120cm computer fan and speed controller

measurements are as follows

riser 70 cm
gap between riser and top inside 15cm
3 inches of rockwool inside a big bit of ducting around the riser and the last bit of the burn tunnel
burn tunnel 33cm
feed (22 degree angle from riser) 23 cm
cleanout 14cm (sits under the feed tube in same direction as the burn tunnel)


and the flue

burner then long 180 degree bend  over 100cm of flue then 300cm straight and a 90degree then 100cm straight and a 90degree pointed down through the floor onto an h cowl

computer fan is in the entry point of the h cowl

have managed to get my 35 foot long truck to 27 degrees!!!

i would like to add mass but needs to be lightweight to a degree does anyone have suggestions?

and criticism as long as it is constructive! i am living on bare minimum so as i can try and put everything i earn into my business! (4 year plan) 2 years to go!

[jacob]

Jan 20, 2014 10:54:33 GMT -8 toby916 said:

ok so after trying to heat myself for as little cost as possible i built a "mass heater without mass"

ThAT'S HERESY!!! TO THE GALLOWS IMMEDIATELY!!!!! 

I don't know enough about rocket stoves to comment on your design. But I will say be conscious of safety before anything else.

You are venturing in to uncharted territory. And existing rocket designs have been proven to be very safe, so don't let that safety record give you a sense of security that your divergent design will also be safe.

Two things come to mind immediately.

1.

make sure you are not accumulating unburned wood gas somewhere in your system that can ignite when you least expect it. For example the end of a burn, you wouldnt want wood gas accumulating because you didn't have enough draw at that stage to suck it out.

2. be very conscious of the heat exiting the flue and or the interface where the pipe goes through the wall.

well 3 actually, also if your system burns really hot all the way through, don't use cheap pipe. The galvanized pipe used in conventional RMH function only because they have cooled the temperature way down before going in to that cheap pipe. So in that setup, cheap ducting can function safely.

If you are creating any design which diverges from tried and true methods already pioneered by people who have perfected them, use as many precautionary measures as possible in case your design has a flaw you did not foresee.

I am assuming you have a carbon monoxide detector in your small space. I would not burn ANY DIY stove design indoors without one.

[toby916]

Jan 20, 2014 20:01:08 GMT -8 jacob said:

Jan 20, 2014 10:54:33 GMT -8 toby916 said:

ok so after trying to heat myself for as little cost as possible i built a "mass heater without mass"

ThAT'S HERESY!!! TO THE GALLOWS IMMEDIATELY!!!!! 

I don't know enough about rocket stoves to comment on your design. But I will say be conscious of safety before anything else.

You are venturing in to uncharted territory. And existing rocket designs have been proven to be very safe, so don't let that safety record give you a sense of security that your divergent design will also be safe.

Two things come to mind immediately.

1.

make sure you are not accumulating unburned wood gas somewhere in your system that can ignite when you least expect it. For example the end of a burn, you wouldnt want wood gas accumulating because you didn't have enough draw at that stage to suck it out.

2. be very conscious of the heat exiting the flue and or the interface where the pipe goes through the wall.

well 3 actually, also if your system burns really hot all the way through, don't use cheap pipe. The galvanized pipe used in conventional RMH function only because they have cooled the temperature way down before going in to that cheap pipe. So in that setup, cheap ducting can function safely.

If you are creating any design which diverges from tried and true methods already pioneered by people who have perfected them, use as many precautionary measures as possible in case your design has a flaw you did not foresee.

I am assuming you have a carbon monoxide detector in your small space. I would not burn ANY DIY stove design indoors without one.

Thanks for the safety advice and yep all covered! if you read on i possibaly sound slightly paranoid now that i think about it....

in reply

1. the computer fan doubles up as ventilation during the day so is left running even when the burner is going out and is cold (although seems i need to learn about woodgas!)

2. the heat from the last part of the flue is just about warm to touch after 4 hours burn time (still going now) so im assuming im doing something right and extracting most of the heat into my room YAY   just wondering what sort of temp a RMH flue gets to? and if its so cold how does it warm the mass?

i have got 2 carbon monoxide angels (digital with readout) 2 smoke alarms, glass fused fire extinguishers fitted in the roof and a handheld powder (im taking no risks this is my only life and my only home!

again thanks for the reply, any ideas on some sort of mass? options i have come across are
1. ceramic floor tiles 10mm thick attached to the gas bottle with fire cement/refractory cement
2. insides from economy night storage heaters (clay thermal mass) stacked around the bottle
3. fire bricks just stacked around the flue and bottle


also another design has come to mind but i will cross that bridge in my next reply

[jacob]

One thing I forgot about safety.

what happens if the fan stop working? Does this make the system dangerous somehow?

for portable mass you should try metal 5 gallon buckets filled with water.

You can stack the the buckets very close to the burn chamber and first exhaust run. Maybe some kind of thermal blanket could be fastened around the exhaust run and draped over the barrels to focus more heat in to them and less out the chimney.

You would need to leave some kind of holes in the lid for steam to escape if the water starts boiling which I doubt it would.

If steam in your space becomes a problem, you would have to rig up some kind of tubing system to route the steam outside.

A little moisture content in the air is good and helps things feel warmer. The flip side is if it starts getting cold, the moisture makes it feel colder.

Water can hold three times as much thermal energy as cob in the same space. so having 6 5 gallon buckets at 150 degrees would be like having 18 5 gallon buckets of cob. at 150 degrees. That's a lot of mass. And it's very portable.

when you need to move just take off the lids, dump the water, and the buckets will stack together and take up very little space, and the stack will be very light.

[jacob]

Just had another idea. You could set up a temperature gauge on the exhaust to run the fan. The hotter the burn, the slower the fan would go, the extra heat would push it out, thus maximizing heat kept in the structure. The colder the system starts to get, the more the fan could start sucking. This would ensure that at the end of burns, unburned woodgas would be leaving and not accumulating. If it gets to the temperature cold enough to indicate the fire has gone out, then the fan could turn off entirely.

However, I would implement such a device ONLY in a way that it ADDS to the efficiency of your system.

You would not want the SAFETY of your system to depend on such a device functioning properly. You should design your system so that no matter what happens to the superfluous parts, the entire system can still burn itself out without creating a safety hazard.

[jacob]

Jan 20, 2014 10:54:33 GMT -8 toby916 said:

Hey a couple more things I wanted to let you know.

My idea for metal 5 gallon buckets is speculative, I have not tried it, I and am not telling you from experience.

As is my idea for the temperature controlled fan, I actually have no idea how that would effect the functioning of your system.

I am doing lots of research right now on rocket type stoves and plan on building some ranging from conventional to radical. But I have not built any kind of stove so far. So take any ideas I have with a grain of salt.

Regarding the 5 gallon buckets, I don't think I clarified enough.

I don't THINK they would start boiling by simply being stacked next to your stove, however if it was me, and they got much above 150 or so, I would probably move them away from the stove a little until you are happy with their temperature at the end of a long hot burn cycle. And to be clear, you want a passive way for pressure to escape even IF they are not boiling. I don't think I worded that correctly the first time.

mainly being that having water boiling would not be sustainable and I think would defeat the purpose. I have no idea even at MODERATE warming temps, how often you would have to refill them, and you DEFINITELY don't want a pressurized system. And don't count on steam escaping around the edge of the lid, because if you had 5 gallons sitting on top of the lid of a 5 gallon bucket below, by the time that pressure built up enough to escape and push it's way past the weight of the can above it, it probably would not do it very politely. And you may very well discover the issue while simultaneously being burned by a several foot jet of superheated steam!



However like you, one of my goals it to figure out some kind of rocket stove design that does not include the traditional mass, I am sure for the same reasons you have gone that route.

I cant really visualize your stove based on the description, but I had a couple questions.

How long of a burn are you getting on one load? How often do you have to add more fuel?

And what is the configuration that is releasing the heat in to your structure so that it does not exit the dwelling? Is that what the "cowl" is, I have no idea what you mean by that.

Also, how much power does it take to run your fan for 24 hours?

Are you running it off of a battery?

Ideally I would like to design systems that do not require things like fans, just because it's one more thing that can go wrong. And also I would like the peace of mind of knowing I can do this anywhere, in any scenario, regardless of whether or not technology is available to me.

However, I am not completely opposed to of using a fan if it is the only way for me to have a small scale heater which does not require a huge heavy mass to function.

If you can describe your setup a little more, I would appreciate it.

Thanks.

-jay.

[2tranceform]

Build a J rocket with a bare barrel/double barrel. Leave out the mass. This will give you good heat output and a clean burn without the mass. Leaving single wall exhaust pipe exposed will also radiate heat into the space. It is also fairly simple to build and proven design.

[Donkey]

Yep.. what 2tranceform said..
You can stack multiple barrels or place them side by side, treat them as bells and away you go.

[jacob]

Jan 23, 2014 8:09:30 GMT -8 Donkey said:

Yep.. what 2tranceform said..
You can stack multiple barrels or place them side by side, treat them as bells and away you go.

I have seen this. I wondered, how is the top barrel attacked to the bottom barrel, does it have to be welded?

And in the side by side barrel configuration, how would the plumbing be wired? And I guess as long as I am getting a hot efficient burn, I don't have to worry about the second barrel becoming a woodgas accumulator?

[Donkey]

Hot, efficient burn = no wood gas!

I think that Peterberg uses aluminium tape to seal his barrel stacks. Not particularly attractive, but easy done.

[toby916]

Jan 21, 2014 21:43:09 GMT -8 jacob said:

Jan 20, 2014 10:54:33 GMT -8 toby916 said:

Hey a couple more things I wanted to let you know.

My idea for metal 5 gallon buckets is speculative, I have not tried it, I and am not telling you from experience.

As is my idea for the temperature controlled fan, I actually have no idea how that would effect the functioning of your system.

I am doing lots of research right now on rocket type stoves and plan on building some ranging from conventional to radical. But I have not built any kind of stove so far. So take any ideas I have with a grain of salt.

Regarding the 5 gallon buckets, I don't think I clarified enough.

I don't THINK they would start boiling by simply being stacked next to your stove, however if it was me, and they got much above 150 or so, I would probably move them away from the stove a little until you are happy with their temperature at the end of a long hot burn cycle. And to be clear, you want a passive way for pressure to escape even IF they are not boiling. I don't think I worded that correctly the first time.

mainly being that having water boiling would not be sustainable and I think would defeat the purpose. I have no idea even at MODERATE warming temps, how often you would have to refill them, and you DEFINITELY don't want a pressurized system. And don't count on steam escaping around the edge of the lid, because if you had 5 gallons sitting on top of the lid of a 5 gallon bucket below, by the time that pressure built up enough to escape and push it's way past the weight of the can above it, it probably would not do it very politely. And you may very well discover the issue while simultaneously being burned by a several foot jet of superheated steam!



yes i was more planning something along the lines of a small empty propane cylinder 50/50 filled with antifreeze/water (prevents rust) with a pressure release valve fitted and poked outside

However like you, one of my goals it to figure out some kind of rocket stove design that does not include the traditional mass, I am sure for the same reasons you have gone that route.

glad to find someone else doing the same thing, glad we are sharing ideas!

I cant really visualize your stove based on the description, but I had a couple questions.

How long of a burn are you getting on one load? one load being about 6 feet of roughtly 1x1 lasts about an hour once its up to temp
How often do you have to add more fuel? i keep it poking out the top so it almost self feeds (angle wrong on feed tube)

And what is the configuration that is releasing the heat in to your structure so that it does not exit the dwelling? Is that what the "cowl" is, I have no idea what you mean by that.

"cowl" is a chimney top for a standard house, i am using the H cowl to help reduce backdrafts.

My J tube exits into a 47kg gas bottle (4mm thick steel) and the outside of the bottle has bits of 6 mm slate attached to it to hold and radiate heat

Also, how much power does it take to run your fan for 24 hours? 0.6a per hour

Are you running it off of a battery? yes i have got 1100A 12v leisure batterys

Ideally I would like to design systems that do not require things like fans, just because it's one more thing that can go wrong. And also I would like the peace of mind of knowing I can do this anywhere, in any scenario, regardless of whether or not technology is available to me.

all you need is a 12v battery and a small solar panel

However, I am not completely opposed to of using a fan if it is the only way for me to have a small scale heater which does not require a huge heavy mass to function.

If you can describe your setup a little more, I would appreciate it.
 i will try and get some pictures up at some point, am re designing the burn tunnel in my mind
Thanks.

-jay.

[toby916]

it seems my reply has come out the same color.... oops sorry!

[toby916]

2tranceform

when you say stack multiple barrels do you mean like a masonry stove where the smoke is directed through lots of channels to extract all the heat? of do you mean just over the barrel to help hold and radiate the heat?

trying to work out on the 6 incher how bit the hole needs to be before the 6 inch pipe.... cant decide of i should make a 12 inch to 6 inch cone to try and help the gas flow or if just welding a 6 inch pipe to the bottom will suffice for flow?

and should i shape the bottom of the barrel to direct the smoke to the exit point... could use firebrick refractory... small bit of mass!

[2tranceform]

Jan 30, 2014 17:39:53 GMT -8 toby916 said:

2tranceform

when you say stack multiple barrels do you mean like a masonry stove where the smoke is directed through lots of channels to extract all the heat? of do you mean just over the barrel to help hold and radiate the heat?

2 barrels stacked is setting one barrel directly on top of the other so that they form one tall cylinder. They form one heat chamber to extract more heat before the exhaust heads to the chimney. Basically, it is the stock construction technique with the second barrel added on top of the first. The top of the lower barrel and the bottom of the top barrel are open. This is a simple solution to extract heat without having the mass.