thomas rubino

Hi Holly;

Yes, you can surround and cover  the riser with bricks and then you could cob those bricks if you liked.

You would want a much larger gap from the top of the riser.  Traditional J-Tubes used 2-3" as a gap.
I recommend having as much as 12" gap and then utilizing a stratification chamber (empty bell)
One thing I think you should do is stay away from a piped solid mass.
They are old school and can require periodic cleaning to maintain flow.

For your little area a 6" J-Tube would be plenty large enough.

Here is some lite reading to get you started
https://permies.com/t/270559/Stratification-chambers-Bells-explained
https://permies.com/t/272271/distinctions-RMH-type

Hi Paul, welcome to
Permies!
European masonry heaters have been in use for hundreds of years.
Then, there are Montana Masonry Heaters, also known as rocket mass heaters.

European heaters use a super hot fire that travels through serpentine channels and heats the bricks.
They are complex to build, and a licensed stove builder must construct them in some states to get insurance.

Montana masonry heaters utilize a rocket core, most commonly of a  Batchbox design.
This core is mounted inside a stratification chamber" bell, " which is really an empty brick box.
The hottest air rises and displaces the cooler air, which sinks (stratifies) to the bell's lowest portion,  locating the exit chimney and leaving the bell.

Here are some interesting threads you might enjoy reading.
https://permies.com/t/270559/Stratification-chambers-Bells-explained
https://permies.com/t/272271/distinctions-RMH-type
https://permies.com/t/267527/Shorty-Core-bell
https://permies.com/t/238503/Batch-Rocket-Build
https://permies.com/t/248275/Batch-Rocket-Double-Skin-Bell
https://permies.com/t/272921/Shorty-Core-party-dress-clay

Chris, are you using the 6# or the 8# density Superwool?
I've only used the 8# and never felt it needed anything.

The five-minute riser on My Studio Dragon is now in its 5th season.
I hope to do a completely new build out there this summer.
The piped mass will be removed, and the existing core will be moved into a brick bell, perhaps double skin if I can collect enough brick in time.
The riser will be reused as is.

Insulated firebricks are the best choice for a riser if you can locate and afford them.
Superwool is a good second choice.
Heavy firebricks, either whole or split and wrapped with an insulating blanket, are a good third choice.

You can use just sheet metal, with rivets or screws to create a 200mm or any size form.

I consider 6-8 months to be the ideal time.
After that, they become very large and have a lot of extra fat.
I get weaners at 8 weeks old and feed them for around 5 months.
I aim for a hanging weight of 180#-200#

Hey Ben;
Superwool is safe until heated to riser temperatures, 1400F and over.
At lower temps, the Superwool remains safe to handle.

After heating, it will form a crust on the surface. If you disturb the riser enough, it will throw dust, so be sure to have a mask on.
As Fox mentioned, coatings are available to minimize that dust if it concerns your customer.

I have opened my cores numerous times and needed to remove the riser. I avoid sticking my face over the riser and simply set it aside while making modifications or repairs.  
Then set it back in place and cob it down.   I use a paper mask while removing and replacing.

When creating a 5-minute riser, with stove pipe, no inner form is needed.
The Morgan is carefully cut with an angled edge. It is self-supporting on the inside, and the stovepipe makes it easy to handle.
A 6" riser takes less than 24" to form, so your riser can be as tall as you desire it to be.
It uses more than 24" for an 8" riser, so you must Stack two sections to get the desired height.

It would be nice to have the burn tunnel, its roof, and the lower riser base insulated, but the entire thing can be heavy brick.
The feed tube and the floor of the burn tunnel should always be heavy brick to protect from abrasion.

Hi Nathon;
I noticed that your core support is cut directly from the barrel bottom.
Bens was cut from a lid and bolted into place. His is flexing, is yours?
Your side plates are taller than his.
It may just be the differences between a cottage rocket and a sauna rocket, or it could be that the plans were updated from Ben's version to yours.

EDIT) I've written to Mud asking for clarification.

Hey Tom;
Is that a brand name?
Or are you looking for refractory brick ( 2500 F or over)

Wow, these are all really great uses!
I do add it to each load of laundry.

But, I have used it for many years to boil deer and elk skulls.
These are known as European mounts.
Generally done outdoors.
A two-step process, that first removes meat and tissue and then turns the skull a chalky white.
Care must be taken to keep the antlers out of the boiling water, which is quite the job with a good-sized elk.

Yes, I think you could carefully cob that, but... using a section of stove pipe or sheet metal wired on first before cob would be more durable.