Peter McDonnell

Hi Fox James, I am planning on an 8 inch riser but this may change. I did provide a link to the plans though nothing is set in stone.  Interesting to encounter another Channel Islander on here,  I was actually amazed.  I was born and raised on the slightly bigger rock.

Peter

I think I am going to give up on the Superwool 5 minute riser at least temporarily, I cannot source the correct thickness in Ireland.  I can from the UK but the unit cost is high plus shipping and then there will be customs duty on top of that. Having looked at the Rocket Mass Heater Riser chapter again I am now thinking of insulated firebrick but slightly adapted to the hexagonal shape shown on batch rocket.eu Other possibilities I am considering are vermiculite board or perlite and clay.  I spent months trying to source a vacuum moulded ceramic fibre tube - but no one would supply to me form Europe.  Cost would probably have been crazy anyway as a one off.  I know I can get firebricks!

Sorry Peter, the floors are stone over Portland cement based concrete over subsoil.  Originally the floors were just earth.

Thanks again to all who have given advice to me here.  I live in the far SW of Ireland  a few hundred metres from the Atlantic ocean - so it has an Atlantic climate.  Frosts are rare enough possibly 10 -15 during the winter but sometimes we get snow that lasts for several days - who really knows these days!  
The main house is more than 200 years old - 700mm + rubble built walls ( fieldstone and  subsoil ) with hemp lime plastering inside. Many of the internal features are original - where we have been able to add insulation we have, but the main part of the house is draughty even with all the windows and doors shut.  This is due to the internal ceiling construction, these are original and we don't really want to change.  There is a wood burning stove in the living area which is on more or less continuously when we are home and central heating running form a heat pump (sparingly) in the winter but the house is cold (obviously) by morning.  

Not sure if any go that helps but it gives some context.  

Thanks Tom and Thomas,
This morning I was looking to source Morgan Superwool.  I have found one company that seems to stock their products in Ireland.  If this is th same stuff it comes in either 8mm or 9mm thickness.  This is the link to the product:
Morgan Superwool Blanket

Is this the correct supercool blanket for insulation and making a 5 minute riser?

Peter

Hi so my first real question.  I sourcing the firebricks.  They are available if 1", 2" or 3" thicknesses but all cost the asme amount (?). $5.50 each. I have attached a PDF of tech specs for the bricks. Would there be any reason to go for one thickness over another for the burn chamber, riser or the bell contraction above the riser?  Was going to go for insulated fire brick for the riser at least, but they are only rated to 1000C (1892 F) which the designer suggests is not enough.  I will now insulate with refractory blanket.

For more information I am planning on basing the build on this resource :Batchrocket.eu

It is the Bell with two benchs.

Thanks for any thoughts

Peter

Thanks so much for the advice.  Unfortunately I have habit of overthinking pretty much everything I do! I appreciate the positivity immensely.  I'll let you know how it goes ,though I won't be staring the build for a couple of months. When I run into trouble I'll know where to go. Thanks again.

Peter

Hi there, this is my first ever post on premise despite having had the forums for a few years.  At long last  I am planning on building a batch rocket heater based on a design shown at batch rocket.eu. This will be my first ever build. Basically it is a bell with two benches, one bench either side.

My question is: in the description it suggests the bell should be built completely from fire brick but at the workshop where a demo was built only the top has was built with firebrick.  It also mentions that in the US the bell would be built with a double skin, the inner fire brick the outer brick.

The less fire brick used the cheaper the build.  A double skin would again be more expensive to make, but would have greater mass.  Can anyone with experience make any suggestions?  At the moment I ma thinking of making the bell with a single skin of fire brick, but in Ireland this is expensive, well everything is expensive.

I am possibly worrying about nothing and should just get on with it!

Thanks for taking the time to read and any advice greatly appreciated.

Peter