thomas rubino

Hi All;
It has been a year now and the firebrick tile roof is as good as the day I installed it.
The RA330 stub was replaced with an RA253 MA stub to test its durability in an extreme burning batchbox.
I am happy to say that it has passed my testing!  
In my opinion, RA253 MA is a suitable low-budget alternative to RA330.

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Hi Brian;
Locate the packing nut #75 and loosen it up.  See if that helps.

Hi Lee;
Welcome to Permies and Welcome to the wonderful world of Rocket Science!
So you want to build an RMH in your basement.
Is this a basement that will be occupied? Or will you need to go down to feed your stove?

It sounds to me that you are thinking of a J-Tube rocket with a piped bench and a solid mass.
I suggest building a 6" batch box with a brick bell instead.
An 8" J-Tube needs wood every 45 minutes, and a 6" J-Tube needs wood every 20-30 minutes.
A 6" Batchbox needs wood every 2 -3 hours or so.

So, about the used concrete blocks.
Concrete does work as a mass but only away from the high-heat.
They could be utilized at the bottom of a bell but not near the core or riser.
Using the 6" hole as piping is just not a good idea in your case.
You could only build a 6" J-Tube with them and that's not nearly enough for an old Victorian home.

I would save those blocks for a different project.

Having worked in refineries many times, I suspect that you will find,
Firebricks both heavy and insulated, full size and splits.
Refractory cement, ceramic blanket and ceramic boards.
What I doubt you will find is fireclay.
A masonry supply would carry fireclay for fireplace builders.

Hi John;
Locate a masonry supply house, any larger city near you should have one.
I pay $8-$14 for a #50 sack in Missoula or Spokane.
In Canada, it is apparently hard to find.
I can ship you #20 for $35 if you can not find it locally.

Hi John;
I used a clay mortar on my outdoor brick oven.
3 scoops of sharp medium sand and one scoop of fireclay.
It makes a beautiful pale white mortar.
I do have a roof over it so I'm not sure how it would hold up exposed to rain and wind.
Matt Walker uses the same mix on outdoor stoves and he says that a springtime touchup of mortar with your finger works well for him.

Hi Dan;

That sounds like a great score on finding pipe!

After the hot 1800F air leaves your riser it is quickly cooling.
Where it enters the pipe system it should be in the 400F  range.
When it leaves your mass and starts its way up your chimney to the roof, the temps are down to 150F-250F range.
Sloping your pipe up through the mass is not necessary.  Heat rising will create a draft

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Hi Matthew;
A cfb core would not require extra insulation on the sides but on the bottom, I would bed it on 2" of insulated cob just to be safe.
The sides of your core should have a "support" backer such as clay bricks.

Hi Joe;
The link to your photos does not work for me here.
Tell us more about your build, what style RMH were you thinking?
If you have what I think you have, sections of a Square chimney liner?
And if you are building an RMH, then they will crack quickly.
It has been tried before and they do not handle sudden temperature changes.

Hi Nathan;
Welcome to Permies!
A few pictures could help identify your part.
As a guess, I suspect the piece is a diverter or bypass that allows you to easily start your cook stove when cold and then divert the exhaust stream around the oven after there is a good draft flowing up the chimney.
If my guess is correct, then without that part installed your cook stove will only vent directly up the chimney and not heat the oven to cooking temps.
All the antique cook stoves that I have used have this bypass, yours should as well.