Gerry Parent

Cerbu Ulea wrote:I am sure the design is good , the tests to run the heater I look forward to. Newish town for me here, hardly know anyone. It is quite solid ,bent from a single piece of cut pipe , except the the small piece above the inlet , that could indeed fall if the tape fails. Should l just make small curing burns and monitor the temperatures, or just wait to weld it myself?

I'd say this is the perfect opportunity to get to know the local welder and introduce him (and others) to masonry heaters.  
Also, you know that you can operate the shorty core for testing purposes without a door right?
Light that baby up and let her roar!

Fox James wrote:Thank you Peter, unfortunately I cant personally open those links on my apple but, I will past on what you have posted.

After downloading the 2 .skp files that Peter linked, go to  SKP Viewer

 
  and click on "open a file" button and select one of the 2 files. You should be able to view them here.  Hopefully this helps Fox.  

Adding chunks of dense materials (like rocks, broken bricks etc) that are all hidden away between the cob will save you a fair amount of time making it and will allow more structure to build higher each day.
Like the clay tiles your using, these dense materials of various shapes can also provide a formwork to support the wet cob and produce shapes that would otherwise be more difficult (and slow) to do with just cob.

Jamey
To keep the stray fire and smoke from coming out the feed tube (as Thomas suggested) try to keep your wood length at or lower than it's height. Also, a brick can be placed horizontally to partially cover the feed tube which increases the velocity and draw the fire will have.

Being an accomplice in this endeavor, I must confess that the muddy water was mostly my fault.

Over the many days of brick laying Shorty, she never showed any signs of being dull or drab until a day or so after she was lit and the bricks were able to start drying out. - This was when she showed us her true colours. It was like watching her age right before our eyes. All the beauty treatments given to her just weren't cutting it..... But she's just a young girl! How could this be?
This made me deeply ponder my own life. Like all of us, as we age, there are certain things we can only control to a certain point before we just give in and accept our impermanence.
We'll just learn to love her as she is and let her beauty be more than skin deep.
After all,  keeping Tom & Liz warm and cozy 24/7 is a beautiful thing.

However, as you already know, Thomas (with Liz's help) has found the fountain of youth and has demonstrated the power of their magic elixir with wonderous results.
Nice recovery Thomas!
My hands have been washed clean so to speak.
Guess now (in this case), beauty can be enjoyed both inswardly and outwardly with great pleasure.

Hi Rico
Welcome to Permies!
Matt Walker has answered a similar question about modifying an existing wood stove to make into an RMH.
Knowing first hand how awesome a properly built masonry heater works, I would highly recommend spending your time towards a full build from scratch rather than trying to make your wood gobbler slightly more efficient.

Hello Shodo,

If  you are looking to build a batch box, Peter van den Berg has given a good write-up about question you asked on his website:

https://batchrocket.eu/en/building#size

Having experienced cold plugs, shoulder season burning, wind gusts, new builds etc which can all be potential back drafting material, I would not build another RMH without a bypass of some kind.
A priming port that Austin suggested would be my second choice... Lower tech (meaning slightly less complex than a bypass to install and bullet proof for anything to go wrong with) but not quite as functional as a bypass (can only be used for priming and as a cleanout/ inspection port).
After deciding on a bypass, the next question would then be what style to choose?
There are simple to complex based on your skill level.
A topic already discussed on Permies but could easily be revisited to help keep that resource updated.

Sounds like your looking at the question from the wrong end John. The vertical height of the chimney is not usually the deciding factor to calculating the amount of heat you can extract and still get a decent Delta T for draft.
The size and design of your RMH is most often asked first.
So, what have you chosen?
Once that is known, suggested pipe lengths or ISAs can then be given to work with (which Thomas and Glenn have already pointed out some of them).
So unless your vertical chimney is exceptionally tall/short,  not built to standards or let's say is known to have constant wind problems that affect draft, you may want to adjust these heat extraction suggestions up or down accordingly.

Coydon Wallham wrote:I've done the tarp thing while learning cob at a couple of places, but always with the cheap plastic tarps. The only one of those I have is about to be retired and I don't want to purchase another. Does it work as cleanly using cotton canvas tarps- will it clog and stick to the fabric too much?

The lumber store/ mill often has used lumber tarps free for the taking. I believe they are just destined for the garbage anyways so this gives them a little longer useful life (amongst many other uses out of direct sun for longevity.)