Pocket Rocket Beer Keg - Stainless steel offgassing??

Its getting cold round here at night and I would love to put in a RHM BUT, I have designed the house to be passive solar AND live in the Mediterranean. So it doesnt really get that cold and I dont want to build the RMH before I have insulated the house to see how warm it is without any back up heat.

In the mean time I have built this beer keg pocket rocket (for use indoors) and would like to know if there is anything I should be worried about, off gassing weird fumes etc?
Apart from the obvious: pocket rockets get really hot, etc etc

Cue Satamax "Put a bell on it!!"

I am thinking about it, just have to play a little more to figure it out.

I have just put a first burn through it and it goes really well and pumps out tonnes of heat.

Any suggestions would be much appreciated!

I wouldn't worry about the stainless steel offgassing, but I would be concerned about smokeback from the pocket rocket feed once it is installed inside. What sort of chimney are you planning for this installation?

Glenn Herbert wrote:I wouldn't worry about the stainless steel offgassing, but I would be concerned about smokeback from the pocket rocket feed once it is installed inside. What sort of chimney are you planning for this installation?

6 inch that will go straight up for about 3 metres /10 feet, then 90 degree bend out the wall and then maybe up again.

it looks as if the genius is in the simplicity and if a temp heater is all you want then by golly it looks like thats what you will have and it will work good until it doesnt. by the time your geter all insulated im sure youll see the metal tubes breaking apart and youl figure out whether you want to build a real one or not. since its a temp system and if i was building a temp system i would run the smoke stack out the best window of your choice and then decide later if you need to keep it so you dont have to patch a hole in the wall.

The stainless won't offgas or melt because its exposed to the colder atmosphere. It will turn a cool bluish purple tho . I love it. But I would have to agree with the bell idea. Is it anti corrosive stainless internally also? Insualted? I have stainless in mine for liners and the liners are still in good shape, same as the steel, after 40 or 50 hours total burn time. And I've burned it multiple times without liners, no problems. However some people have super insulated their metal rockets and had the steel rapidly degrade, not mine, but I've seen photos and stuff others have shared on here, that's why I got nervous and installed anti-corrosion hi-temp due-therm stainless steel liners.

Consider a stainless steel refillable fire extinguisher for a bell! Small enough and big enough to fit your keg .

I love hot rod and steampunk sh- er.. um... stuff. Beer keg is epic awesomeness level of cool.
Good work.

F Styles.

Not many people insulate pocket rockets. As they are temporary units. They're suposedely more efficient than a wood stove. Usualy don't last, even with no insulation. The bottom of the barrel rusting away in a few months.


Luke, stainless doesn't offgas. It's a compound. Components are atomicaly bonded.

But two words of caution. Put a thick slab of whatever you can to protect your floor. Even if it is concrete, it might explode under the intense heat delivered by the bottom of this thing. And carefull going through the wall, is there is any flamables around. Even the pipe might get rather hot.

And this should last a bit more than your usual barrel pocket rocket, as it's stainless.

John McDoodle wrote:The stainless won't offgas

thanks for the info John.

John your little larger than pocket portable rocket stove is a little over a month, is it showing any signs of rusting through the bottom? mine is about two months old and i dont see any rust in mine.

Fstyles:

My steel 5x5" burn chamber tube and the feed tube are both fine on mine after about 50 hours developmental burn time testing. I have inserted stainless steel hi-temp anti-corrosion duo-therm liners and they are great shape, but the liners are thin material and they only have about 12 hrs on them, but they are being used as replacable liners, so if they do deteriorate some day, the liners can be easily serviced/changed.

What's in the bottom of yours Fstyles? Steel? Or stainless? I didn't know that your stove was so young...

John McDoodle wrote:Fstyles:
What's in the bottom of yours Fstyles? Steel? Or stainless? I didn't know that your stove was so young...

yes my stove is only a few months old at most. if you check my diagram on my thread you will see i bolted a half of a 55gal barrel onto a full size one and its just a barrel bottom whatever the thickness of the barrel steel is. its just steel buddy and no rust. its a heavy barrel for sure...one of the best in my opinion. i poured 1" loose perlite on the bottom then refractory cement then built the fire bricks then poured another thin layer of loose perlite on the sides then the portland perlite mix. loose perlite has at least twice the insulation factor for sure. my heat riser concept is absolutely amazing. it was so hot i had to cut an inch off the heat riser so my lid didnt melt. my firebricks get so hot they glow orange.

even the stock paint on my barrel is crazy it wouldnt burn off, smoke or off gas when i tried to burn it and it wouldnt come off.

Here is an update on my experimentation with this...

So, it burned really well and got really hot, but the draft is so strong that it is just pulling all of the heat up out the chimney.
I have put a bell on it and this works much better but it still is drafting way too strong. I have to cover the feed tube with fire bricks and leave just a little hole so that it doesnt burn so fast.

I think that the draft issue is because I am using 6 inch stove pipe. I bought this size pipe so that I could eventually use it on an RMH.

Another thing is that I have to attend to it almost constantly. Once it gets to a certain temperature, the whole piece of wood inside the feed tube catches on fire.

My house is really badly insulated but the temperature in the inside doesnt even get to 20 degrees C with the pocket rocket/bell full blast/red hot and going through a bunch of wood.

I am thinking of giving up for the moment and just getting a cheap traditional style firebox stove for the last couple of months of winter.

Its a bit sad to give up on it but its just not practical and its not like its even heating the house much.

I think I might look into building something like one of Peter Van de Berg batch box stoves in the future.

I will put up a video so you can see it burning although its not really working much as a heater at the moment so dont know if its really worth my time editing the video, etc.

hey...

just my opnion. you have good draft and not enough heat-into-the-room. did you measure exhaust-gas-temperature?

what i am thinking of, is adding more bells sideways. like stove leading into a barrel/bell leading into a barrel/bell leading into a barrel/bell leading into a barrel/bell leading into the chimney.

that would help increasing the amount of heat-extraction

any thoughts on this?

blessings
tobias

how big is your home? perhaps a thermal mass for energy storage would help depending on the exhaust temp

not very big about 100 sqm (1000sqft) although we do have very high ceilings, about 4.5 metres high.

The mass would make a difference in the long run for sure but not in instant heat.

Its been a long time since I measured the exit temps but they werent that high, maybe 50 C after I put the bell on it .

Luke Smith wrote:not very big about 100 sqm (1000sqft) although we do have very high ceilings, about 4.5 metres high.

The mass would make a difference in the long run for sure but not in instant heat.

Its been a long time since I measured the exit temps but they werent that high, maybe 50 C after I put the bell on it .

So that's too small a rocket for 100m².

I'd say 6 incher batch with mass might work all right for you. But with that tall ceillings, may be an eight incher is in order.

Check this one. Not perfect, but works nicely in my woprkshop.

http://donkey32.proboards.com/thread/1817/starting-build-220mm-rocket-double

I need three burns a day to keep the whole 113m² at 12C°, with 6.5m ceilings. And a R1 in the walls and R3 in the roof.

Here is a video showing some temps and how it burns:


Satamax: So you think its simply too small??

We have 0 insulation. the house was an old cow shed. we will be insulating thw whole envelope this summer, and then see what the temperatures are like next winter before making a decision on the heating source. we have a good south facing exposure with around 12% solar glassing on the south and very sunny days for most of the year. Hoping that once the insulation is done that passive solar will work its magic and provide most of the heat.

Thanks for the links. I am thinking about a batch rocket for the future, it would fit well in the space and you get to actually see fire.

Luke, what are your temps in the winter?

What do you plan to insulate with?

Right now its 5 degrees C outside and 10 degrees C inside.

The average temperature for the year is 15C.
Lowest is probably -5 but that is maybe 1 or two days a year and its only really cold from end of november to April.

The thing here is that if its sunny it will be 18 - 20 C at lunch time.

We are insulating the walls (outside) with 5cm of cork
The roof will be insulated with 5 cm of lightened cement using expanded clay on the outside and a new product made of recycled clothes on the inside. maybe 10cm. cant find the product of the r value for the moment.

This is where I live:
https://es.wikipedia.org/wiki/Algaida

this is what we got for the next week:
http://www.eltiempo.es/algaida.html

The exhaust pipe looks very reflective. It probably isn't giving an accurate temperature reading and there could be substantially more heat going out the exhaust. If it is drawing air in that well then that air must be coming from somewhere. It could be that it is pulling an amount of cold air into the house that is killing the efficiency of the stove. In an uninsulated space it probably only effectively warms up the area immediately around it. You could set up one of those reflective emergency blankets and sleep between that and the stove to stay warm but I doubt it could warm the house as-is.

Adding some sort of restriction to the exhaust could help slow down the burn. I remember seeing a video with the exhaust routed into a second barrel that was filled with bricks as a thermal mass, but I can't seem to find it at the moment. Rocks or other mass could also be used. It wouldn't heat the entire place but it could be enough to hold you through till it is warmer when you can build a better stove/heater.

here are some tempos for year round although it is slightly colder in our area than this, for example our minimum is -5 for dec-jan-feb and it has been known to freeze in our valley randomly up until end of march, but it give you an idea

Daniel Schmidt wrote:The exhaust pipe looks very reflective. It probably isn't giving an accurate temperature reading and there could be substantially more heat going out the exhaust. If it is drawing air in that well then that air must be coming from somewhere. It could be that it is pulling an amount of cold air into the house that is killing the efficiency of the stove. In an uninsulated space it probably only effectively warms up the area immediately around it. You could set up one of those reflective emergency blankets and sleep between that and the stove to stay warm but I doubt it could warm the house as-is.

Adding some sort of restriction to the exhaust could help slow down the burn. I remember seeing a video with the exhaust routed into a second barrel that was filled with bricks as a thermal mass, but I can't seem to find it at the moment. Rocks or other mass could also be used. It wouldn't heat the entire place but it could be enough to hold you through till it is warmer when you can build a better stove/heater.

Yes, it only heats up the direct area around the fire and our house is anything but air tight so as you have also pointed out it is pulling air in from outside. Sleeping isnt a problem, hot water bottles and thick duvets do the trick.

the second bell made it radiate heat a lot better. it works to a point but its too much of a pain in the ass to keep on feeding it every 5 minutes for the amount of heat it gives off. I think in this case the rocket effect is too strong and pulls cold air in . to sort that out i could give it an external air intake but cant be bothered to drill another hole in my walls.

giving up for the moment and going to get a traditional wood burning stove for the rest of the winter. back on the project next winter.

Luke, why not transforming it into a quick batch rocket? There must be a way where you are.

Satamax Antone wrote:Luke, why not transforming it into a quick batch rocket? There must be a way where you are.

yes, I would like to but dont have the time to play with it any more this winter. I have been checking out the stuff on the donkey 32 forum and have to do a little more homework before understanding how the batch rocket works but thanks for your help.

Do you have access to firebricks, or even ordinary old red bricks? If so, there are pretty simple directions for making a batch box and proportioning it correctly on Donkey's forum. Even just feeding your existing "bell" setup should work better than what you have.

Glenn Herbert wrote:Do you have access to firebricks, or even ordinary old red bricks? If so, there are pretty simple directions for making a batch box and proportioning it correctly on Donkey's forum. Even just feeding your existing "bell" setup should work better than what you have.

Hi Glenn, yes I have some fire brick laying around. I will see if I can find the thread in the other forum you are talking about. If you knew of a particular thread that has that info and could point me to it, that would be much appreciated!

fan blowing at the stove? damper in the chimney? some bricks stacked around the stove against the wall? large pot of water on top too?

http://donkey32.proboards.com/thread/734/peterberg-batch-box-dimensions

There are other threads describing the overall system, but not in such concentrated form.

Glenn Herbert wrote:http://donkey32.proboards.com/thread/734/peterberg-batch-box-dimensions

There are other threads describing the overall system, but not in such concentrated form.

thanks a lot!!

Well, if this could be of some interest.

https://permies.com/forums/posts/list/35569#344806

Check this build and the tubes i'm using.

Landini, tona, schiedel and a few others make thoses. If you could find some. You could transform your pocket rocket into a batch very quickly.

While nickel and chromium compounds can be toxic if ingested in significant quantities, this doesn't seem likely to happen.  The most likely compounds to form would be oxides.  Even if some oxides flaked off and a kid or dog ate them, there probably wouldn't be enough to cause a problem.  On the other hand, better safe than sorry.  I would keep corrosive cleaning materials or other chemicals away.  Be mindful of any material flaking off.  It might be a good idea to paint it with high temperature stove/BBQ paint for these reasons and for the following reasons.

Here's some additional info.  Even though stainless steel (SS) won't oxidize/rust/corrode as much as steel, there seems to be a bit of a problem with using it as a radiator.  It may not radiate heat very well, whether it is shiny and new or tarnished from heat.  At high temperatures I figure it oxidizes to Black nickel oxide, which is an ideal absorber of infrared radiation and light, (as comprises solar radiation), but it is a poor radiator of thermal radiation.  It is a rare material, a so called "selective surface" with *very* low "emissivity".

This means that stainless steel has to heat up to *Twice!* the temperature of steel to radiate the same thermal radiation (not including convection)!  This means that 1) the RMH probably is less efficient with SS than with steel, because it may not cool the gases as much and will have to rely more on the RMH mass for efficiency.  2) In theory it also may not generate as much draft.  3) Some of the benefit of the corrosion resistance of SS is lost because the temperatures are higher.  And if you have to paint it or plaster the surface for any of these reasons, then it's perhaps not much better than plain steel.  4) The infrared thermometer won't give an accurate reading on the SS material unless it is corrected or calibrated for emissivity.  5) SS is more expensive than plain steel.  


sources:
http://en.wikipedia.org/wiki/Selective_surface
search this link for "stainless steel":  http://www.redrok.com/concept.htm
http://en.wikipedia.org/wiki/Infrared_thermometer