Starting the next build. 220mm batch rocket, double bell.

[satamax]

Guys, what would you think i should stuff between thoses bricks and the chimney? Sand or grout?

I don't want to have everything pushed to the other side when the bell heats up.

[peterberg]

I wouldn't use sand for that application unless it's stabilized. Just enough to prevent compacting over time due to expansion and contracting caused by the thermal cycle. When used as loose material you run the risk of the walls are pushed apart by the sand.

[satamax]

Ok Peter. Concrete it will be then.

[patamos]

Same thoughts about sand.

Are you sure you want that heat transfer between the bricks and chimney? If not, maybe use rock wool and then a nice thick cob plaster Might be resilient enough to handle the movement.

[satamax]

I don't want too much heat transfer between thoses bricks and the chimney. That's why i thought about sand.

[patamos]

scraps of drywall ?

[satamax]

I've held the front bricks with ciment prompt. I don't want to stuff that with rockwool. I'll either concrete or fill with sand, and be it! I want the bricks to be held tight against the bell's wall.

[satamax]

May be soon to be called a mass heater.

[satamax]

Cannot wait for it to dry out!



I burned it for may be 4 hours today, while piling up thoses bricks and filling them.

And i've had dark glow!




That's for thoses who know what that purple is.

But i have a problem. The air entrained concrete slab on the left when looking at the firebox, has cracked. I might have to build a wall there. Not good! And the right hand side refractory slab cracked too. Mind you, that's far easier to cure, as it is normal and expected.

[morticcio]

Will the air-entrained slabs last? I would use some Superwool or IFBs if available.

The purple glow is always good for melting the aluminium cases from 3.5" hard drives I have stripped down. Put them in a stainless steel balti dish, insert into firebox, cook for 20 mins, remove and pour into the frog of a London Brick to get perfect ingots :-)

[satamax]

Morticio, i was talking about the purple glow in the port!

My camera has a lousy infrared filter, as many digital do. And to me it looked dark orange. I mean, the heat riser was glowing. I've seen that few times on the green machine even the whole end of the firebox. It's a first time for this one. Never happened with the barrel one which was in place before this.

I don't know hos the air entrained concrete will fare. I thought, protected by the firebricks, it could last. But one tiny crack already, that's no good. Mind you, it's easy to replace.

[satamax]

[satamax]

I would say, it's prety much finished.

Did a nice pebble and concrete lasagna on top of the second bell.





Now this is all covered with concrete. I used all the brick rubble from the build. The gravell and sand i had outside. Nothing left or nearly.

1500kg of sand, 8 bags of cement. A wheelbarrow of rubbble. Another one and a half of gravell. Three or four wheelbarrows of big stones. All the hollow bricks visible. A fair bit of old refractory bricks. Plus the dark flue elements, refractory tubes and slabs etc. A fair bit of mass i would say.



Peter, if you see this pic below.




Would you think that, when i reach this ember stage, i can close the gate at the end of the second bell, to stop the heat being wasted into the chimney?

The gate you can see at the beggining of this build. I would think i have something left, like 20% of the 25cm diameter pipe it was originaly made for. I'm trying to learn to make the most out of it.

THanks a lot and best regards.

Max.

[peterberg]

Max, I would say close the air inlets completely and let the coals die down on their own. That's what is being done in Austria with the eco-firebox. The next burn will be built on top of the remaining coals. Closing the damper at the end bears the risk of carbon monoxide escaping into your workspace. You should avoid that at any price.

[satamax]

Ok Peter. The issue is, the door being a smidge big, i did an air inlet all around; i mean i have 6 or 7mm gap between firebox at the bottom, and the door, that going to nothing on top. So, i can't realy close that


The mass on top was still warm this morning. I Wonder if the concrete released all it's moisture, but it kept warm. Mind you, i didn't have to dry the stones, and it's full of thoses

Another question, do you have a lot of ashes? I find that i have alot compared to the firebox of the green machine. Tho, that one was all doubled with IFB. I'll try to post a pohto tonight.