Steven Williams

Thanks Bob, that's an interesting idea, contrary to everything I have seen before, I am sure the Wisners and Mr Wheaten would have a thing to say on it :-)

The only thing I think I would change would be trying to insulate the heat riser.  I used thick fire bricks thinking that that would be enough, but now I wish I had done more. Hey ho, seems to still be putting out good heat though.

I plan to run it for a week as much as possible to get it settled in and for the moisture in the brickwork etc to clear.. then I will see if tweaking is required.   The draw seems pretty good most of the time though

Cheers

The riser is made from fire bricks.... That insulation you mention is not available in Russia where I live, I am constantly having to compromise on materials here as only the most basic things are available.... This is all new to me so I am hoping for a steep learning curve. On the third burn my passive solar greenhouse got to 14c with a starting temperature of 2c.  And that's with exposed pipes.   But was a 5 hour burn.

If I get into trouble then I can swap out the chimney section for 20cm diameter galvanised pipe as the most obvious potential issue.

One can read all the theory there is, seems to me that there is a practical element of just ' making it work ' with what you have to RMH.

The heat riser is the same size as a 20cm tube circumference.  I got the plan directly from the Wisner's book for an 8 inch system.  The pipes are, or rather will be in a (clay/sand) bench.   Since I posted I have completed the system as mentioned with smaller chimney diameter (18cm as opposed to 20.5cm) and it seems to draw ok....getting a bit of smoke occasionally from the feed tube.   Now we have temperatures of -4/5c outside  and the three times I have fired it up it works well so the small changes in diameter of tubing seem to have had no effect.   Thankfully

Hi, I really need some urgent advise.  I am.building my system now,. There are two lengths of steel pipe 20.5cm diameter.  They will be joined by a u- bend fitting but I have just discovered that this is only 20 cm diameter.  Will this effect the draft?   Also. If the vertical chimney was 18cm instead of 20.5cm how would that effect things?

The u- bend was sold as 20.5 cm... It arrived today and I discovered it was a fraction smaller.

If it does effect things, am I right in thinking that fan in the chimney will solve the problems ?

Thanks, any helpful advise received will be greatly appreciated

Steve

Thanks for the detailed reply.   Yes, I certainly need to do some research on batch box design. It gets pretty cold here... -30/-40 F.     I have a thermal battery system which I hope will help a bit. As for making half the heat exchange 'pipe' , from brick.... Another interesting idea.  I was very happy to get the steel pipe as I thought it would hold heat for longer but I always knew I was limited.  I could use the 4 meter long section I planned for the chimney as additional heat exchange pipe and simply build the chimney from something else.

You have given me some interesting ideas. Thanks Thomas..... I think I will be putting a new design drawing up soon :-)

Thomas, I would not need a 180 degree bend as you said I could use the brick bell....   I just don't have enough pipe.  

thanks for your comments Thomas.  

The pipe was salvaged from a derelict Soviet era factory.... I can not get any more, it's very very heavy (it took 5 men to move it) so to buy more would cost a fortune. Also I do not have a 180 degree section to weld in. I have a smaller length pipe with a 90 degree turn which is destined for the chimney section after the second bell. also space is an issue as I have the plastic pipes for my underfloor climate battery on the edge of the mass. so stuck with  the single long steel pipe.  

As for a Batch Box system v J-tube... I had not given that any thought. May I ask why do you think it could be a better option? I don't really know much about a batch box.

I am going to build a RMH in my passive solar greenhouse in Northern Russia. Reading about a second bell chamber got me thinking about my design.   I have a single straight 3mm thick steel pipe running 6.5 meters.  I am concerned about losing heat as there is no 180 degree turn in my system. Would a second bell capture the heat before it vents outside?  Or would there be draft problems?  I will be using this in severe cold... -30c is normal for us in winter



I would appreciate comments from anyone on the forum..... I only know what I read in Erica and Ernie's book and seen on YouTube.... So that's me, a total newbie

Cheers Steve

Just when you think that you have it all figured out, you realise that you actually know very little :-)   adding a bell to the end of my systems sounds interesting, thanks very much for bringing it up. So.... delay the start of the build , downloaded Erica and Ernies book, a day of intense reading.....and maybe a new design by tomorrow.  

Thanks Glen.  I am building the whole j-tube from fire bricks so can make it to match the steel pipe ( square riser, round pipe ).   The metal pipe is not a stove pipe as such, just something left lying around a derilict Soviet factory that I dug around in.  But it is thick  .

Here metal chimney pipes are made from stainless steel....  yours are  commonly what?  aluminium?