Cobbling up a workshop heater. With cooktop, and oven, 4 tons mass. 220mm batch.

Hi everybody!

Edit: Guys and gals, lots of pictures are at the bottom of this thread. It takes a long while to load. The thing has evolved into a 220mm batch rocket with four tons of mass, cooking plate, oven, and may be soon a bench upstairs.

Edit number two, last year i added a nice cooktop direct link https://permies.com/t/44806/Cobbling-workshop-heater#787978

Edit three, transformed the bell into a black oven, as of october 2019, direct link https://permies.com/t/44806/Cobbling-workshop-heater#993907

Well, i spent some time at my new workshop, making a prototype, to see what's possible.

It's a seven incher core, with lousy dimensions for the firebox. At 3 barrels for the moment. I hope i can get 5. It's all drafty, there's gaps as large as 1/4 around some tubes, and nothing leaks outside of the barrels. No P channel for the moment. No door.

Hey Max, your new shop batch-box prototype looks like it should throw some serious heat. Nice looking build.

That is an interesting heat riser made of double-wall Class-A? insulated metal chimney pipe with the addition of an inner square liner. Is the square inner liner made of insulating refractory?

Byron, i't the Landini flue elements i have been prototyping with for a while, they're refractory with grog, suposed to cope with 400C° continuous, 1000C° for 30 minutes. They seem to hold well. The shiny bit is a bin, reclaimed from a skip Insulated with a mix of perlite and vermiculite. For the moment, it's soo drafty with gaps, that it cools off way too fast! Talking with Peter about adding rocks, and may be two more barrels!

First burn from sunday night. There's holes everywhere, and none smoking back.

On my way, or should i say it's alive!


Yeeee fucking hell haaaaaa!

This is a cross between my two systems, the current one, and the future one.

Can you imagine a 18cm square heat riser. With a weird shape uninsulated batch box, and V bottom secondary air. Running a 8.21 ISA all metal double bell?

Here it is!




You just can't immagine how chuffed i am. That exceeds previsions. A 7 incher, supposedely could cope with may be 8m² of massonry single bell. Here i'm in double bell mode, with all bare metal arangement.


Madness, i tell you/

About 8m high chimney. And 20x20 sqare with rounded corners.

From

http://donkey32.proboards.com/thread/1757/floor-secondary-air-channel

Well, sorry guys and gals. I never thought it would work that well.

Some guys at Donkey complained that the pics weren't visible anymore. So,  i re post these here. In hope it can help people.

Sum more.

And another batch!

Final pics of the original thread.

Since then, few mods have been done.

I added a fugly firebrick wall, to hold the air entrained concrete blanks.  (thr white stuff) Which were cracking because of the core pushing on them, and because of the heat.

Lately, i added a nice cooktop, given by a friend.

And made a grid shelf, yesterday, to use as a oven. This is lovely unexpected result. It works wonders, but, I have burned myself twice in two days.

Cooking on the new cooktop.

And the result of three winters of intense heating on metal.

This is the bottom of the metal tank, where it acts as the firebox top. With the already replaced once P channel. I stuffed all this with rockwool for this winter. I'll see what i feel like doing yo repair this one of those days.

The top of your firebox looks like it's heavy steel.  What thickness is it and doesn't it get too hot to cook without burning?

Graham Chiu wrote:The top of your firebox looks like it's heavy steel.  What thickness is it and doesn't it get too hot to cook without burning?

15mm steel. 47x80cm.

And since the firebox is not everywhere under, i can regulate the heat by moving the pot. You should make yourself one of those rocket. Perfect for cooking. But if you don't need the heat, forget it!

Might be good for pizza though.  What temperatures are you recording on the cooking plate over the fire?

Looks good Max!  Great photo's .   Thanks for showing us the updates !  Dinner looks very good...

Great, there seems to be so much scope for fresh ideas and your cooking plate at a sensible height is inspiring.
I would not of thought it gets to hot?

Fox James wrote:Great, there seems to be so much scope for fresh ideas and your cooking plate at a sensible height is inspiring.
I would not of thought it gets to hot?

I don't get the thermometer out often, so i haven't tested the new plate, but hot enough is the word. Basically i i sprinkle a handful of water on the steel plate, and if it rolls, bubbles away, without wetting the plate, i know it's a bit too much for cooking directly on the plate.

https://en.wikipedia.org/wiki/Leidenfrost_effect

One thing, when i will need to change this riser. I will most certainly make a broken riser

http://donkey32.proboards.com/thread/1023/accidental-discovery

To be able to use the full front window as a oven.

Satamax Antone wrote:

https://en.wikipedia.org/wiki/Leidenfrost_effect

As this occurs just under 200 deg C, isn't that the right temperature to sear steak ( Maillard reaction )?

BTW, I'm a little confused about the use of steel in your burn chamber.  Aren't we told that we shouldn't do this?
Or is it the expectation that you will need to replace the steel in a few years time?

Graham Chiu wrote:

Satamax Antone wrote:

https://en.wikipedia.org/wiki/Leidenfrost_effect

As this occurs just under 200 deg C, isn't that the right temperature to sear steak ( Maillard reaction )?

BTW, I'm a little confused about the use of steel in your burn chamber.  Aren't we told that we shouldn't do this?
Or is it the expectation that you will need to replace the steel in a few years time?

Yes Graham, but when you have no choice!

I had tried a metal cooktop on the firebox of previous batch prototypes, and that survived. So i thought my square "barrel" would survive, but it didn't. Normally, the whole stove can be dismantled, without touching the bell.

Max, have you had a chance to record the temperature of your cook top, and inside your black oven? Are you getting fly ash in your oven?

Graham Chiu wrote:Max, have you had a chance to record the temperature of your cook top, and inside your black oven? Are you getting fly ash in your oven?

Cook top is often around 190/200C° near the barrel.

I often measured the outside of the "barrel" inside of  which the oven is.  At around 280/300C°

And i don't find the fly ash to be much of a problem. I am yet to find fly ash on my sausages for example.

HTH.

Since I asked the question I put cast iron, and then a terracotta tile over the burn chamber, and reached 380 deg C with a little assist from a fan But also kicked up some fly ash.

The  permies.com  e-mail said  "Any ideas how he could make it into a science fair project?".
Well, I'm a science teacher.  Here are some thoughts.

1.  The pictures are a good idea.  They show the steps along the way.  Some kids buy stuff and try to turn it in as their work.
2.  Acknowledging changes and mistakes and do-overs are good.  It lets me know you are thinking and working through problems.
3.  The number of pictures are a little much for a presentation, but, fine for a forum.
4.  If you can make it portable and bring it in that would be best.
5.  If you CAN NOT make it portable - make sure your pictures show you in some of them.  You want to have proof you did this and didn't just download pictures.
6.  Having your display include evidence of your work is a good idea.  Maybe show parts and pieces.  Maybe show some of the same tools that are in the pictures.
7.  A poster should be neat, well organized, and legible.  A professionally made sign makes me think a kid thinks they can buy a grade.

I realize it's been a year since the original post, but, maybe this will help someone.                

Phil; what are you talking about?

Satamax Antone wrote:Phil; what are you talking about?

The link in the permies.com post said - Any ideas how he could make it into a science fair project?
That implies someone is thinking about taking this to a science fair.
Being a science teacher I know a little about science fairs.
I was giving advice for what I'd be looking for in judging a science fair.

That's weird.

Hi everybody!

Well, in order to use the upper part of the bell as a oven. I need to break the riser, well, make a broken riser.

I made a five minute snorkel, that i will try.

Here are the pics of this contraption.

I hope i will be able to try it later today.

So the snorkel is done.  And oven stone fitted.

I need to burn it better than last night.

First pic, is the snorkel bottom.

Second is the heat riser after 4 years of burning. Those landini flue elements can take a beating, but they crack badly.

Pic three is the new flue element for the heat riser. I didn't change the bottom one, as it is more complicated. Just the second one. And the third one is gone, replaced by the snorkel.

Pic four is the inside of the snorkel, with the flue element sticking out a little bit. Sure it is not that clear.

Fifth is the snorkel in place

Sixth and seventh is the oven, with the stone lying on the snorkel. And you can see the old grid that i fitted last year on the right. Not very useful. It was always complicated to get things in and out with the old heat riser in the way.

Pic eight is the pieces of the old heat riser. It's shattered. You can see the browning of the inside of the clay. I wonder if they could make flue elements like this tougher. Mind you they are designed for 400C° maximum temp.

Well, my draft increased seemingly.

It was windy today.

chimney temp seems to have raised. I was about 120C° at mid burn.

I cooked a cabbage sausage.

Well, this mod doesn't seem to tickle the fancy of lots of people.

I can’t really understand what you have done, perhaps a diagram of your broken riser and snorkel would help me?
I am interested but the phots are a bit confusing.

Fox James wrote:I can’t really understand what you have done, perhaps a diagram of your broken riser and snorkel would help me?
I am interested but the phots are a bit confusing.

Well, originally

The front door was meant just to assemble the heat riser




Then, i discovered that with a welded grid across the bell, i could cook  in there





But it was impractical, i kept burning myself.

So i thought, since the DSR and broken risers are already exist. I could may be break the riser below the door's  height.

So i removed the top course, 50cm of height, of the heat riser.   Then cut the gas bottle.  and lined it with superwool.  And fitted that above the second course of the heat riser, that i have changed.





And i have laid a huge wood oven slab that i have over the gas bottle and a angle iron that i have welded behind the door.



And you can still see the grid visible in pic number two of this post



So the side of the stone is all open to the bottom of the bell. and the heat riser.

I might have to make a ramp to somewhat force the gases up that hole; a bit.

Get it?

No I still don’t quite get it (sorry)
Something like this perhaps?

Well, having done it, it seems soo simple!

Delving into pizza oven territory.

First burn ember stage. No flzmes

And reloading a forearm size branch. And a siding plank.

Flammes.

That's a pretty thick pizza stone. How long does it take to transfer the heat from the underside to the cooking side?