8" / 200mm Half Barrel prototype - for indoor installation

[uga]

Hello Ladies and Gents.

Special thanks to Matt Walker who helped answer my questions of how to piece this project together! Here are the pictures of my Half Barrel project I just completed. This has been a very fun experience and once I got my hands & feet dirty with the cob, it was an "ah ha" moment of realizing all of the concepts so eloquently pin pointed on this forum and the book I purchased from Ernie and Erica. 

drive.google.com/drive/folders/0B9vq2cFU3w0dTFAwSExPbW5vM28?usp=sharing

The next step is to move this already mixed masonry inside. But first build a 8" / 200mm batch box to provide the power to charge this battery. I like the 4: Straight cast core, 5 parts batchrocket.eu/en/designs#core4 but am now leaning towards the 5: Cast sidewinder, 7 parts batchrocket.eu/en/designs#core5 for the obvious reasons of space for an in-home installation.

The installation will be a slab on grade with the primary heating needed for the second floor of a 150m2 home. Therefore, I am planning to use the same floor channel concept as E&E's 8" Bonny but in a L shape using Half barrels as dead-end bell. The firebox and barrel will be placed in front of the existing insulated masonry exit chimney with an above roof clearance. The L shape will comprise of 3 meters from the firebox to the corner an additional 3 meters thereafter.  

Please feel free to share your insight to my Questions which are slowing my progress.

1. I am having difficulty visualizing how to connect the exist flue to the half barrel system with out all of the heat running up the chimney. Peter van den Berg's Bell with dead-end benches batchrocket.eu/en/applications#culdesac solution comes to mind. How would this be put into play for this kind of application? 
 1. A) Connecting a cylindrical 8" / 200mm at the end of the run comes to mind for a heated back rest all the way to the exit flue... 

2. I assume the half barrels are kept level the entire duration of the run unlike the stove pipe which is slightly elevated at the end of the run? 

3. Would a high mass ~6 inches still be suitable for this application? 

4. Since the door is not ready for installation would it be enough to bury metal strapping in the masonry around the fire box for future add-on? 

Thanks in advance!

[matthewwalker]

For the exhaust, when I came up with the half barrel system I had the same issue. My solution was to push the chimney down through the half barrel so it is positioned just above the floor. You can use spacers to hold it up. Doing this you can essentially lower the chimney exit to allow the half barrels to stratify. I played with the final elevation by sliding the chimney up and down while burning to find a good position that both heated the bench and had draft.

Barrels level if possible in my opinion.

High mass is suitable if you desire a long heat cycle at the expense of slower warm up.

That's a good way to prepare for a door, in my opinion.

Good luck with the build!

[pinhead]

The most important thing you have to remember when building a bell is, the outlet of the bell - the inlet to the chimney - should low (without restricting flow).

The "ultimate" (in terms of producing the maximum amount of stratification for a given volume) would be using a hole in the floor of the bell leading to the chimney.

You can tailor the amount of heat extraction within the bell by changing the height of the exit.

In my half-barrel system I used a register box:

[uga]

This incredibly helpful thank you both! 

[Orange]

I'm amazed how much weight can these 0,5mm half barrels withstand!

how warm are the edges of the bench compared to the middle?

[uga]

Don't have a laser temperature gauge yet, but the hindquarters of my guests approved the overall performance of the bench many times over. The strength of the half barrel form did not come until it was filled with cob and allowed to harden. Especially where I span the gap of letting the two barrels into each other. But once the monolithic form of cob hardened it was just as solid as rock and plenty warm all around

[uga]

Added pictures of v2 drive.google.com/drive/folders/11alv7UyyIuIuL3LKVfP-L7PEV5RuZBBS?usp=sharing

For measurements thus far I have 87cm wide and 310cm long for the long bench and 87cm wide 100cm from the corner. I have decided to build a brick bell like Peterberg's design at the MHA.
I understand the footprint of that build to be 129cm wide and 178 high and I plan to use almost the same plus extending the bench another meter on the left hand side.
The 8" / 200mm batch box will have enough power to heat this amount of M2, right? Please check my math!
For the top Cap I am planning to use silicate insulation board. What thickness should I chose my distributor has from 3 to 6cm thickness. Also what temperature should it be rated for? Is 1000C enough or should I chose the 1260 - 1400C rated material for the ceiling of the bell? 

Thanks!

[pinhead]

An 8-inch batch box is a beast of a machine, indeed. It's scary how much heat an 8-inch batch box will produce. Honestly I'd run a 6 inch batch in that small space.

[Orange]

I've heard calcium silicate boards are ok if they're not in direct contact with flame. I'm curious what climate do you have, any insulation under floor tiles?

[peterberg]

Nov 17, 2017 3:39:44 GMT -8 uga said:

...I understand the footprint of that build to be 129cm wide and 178 high and I plan to use almost the same plus extending the bench another meter on the left hand side.
The 8" / 200mm batch box will have enough power to heat this amount of M2, right? Please check my math!

I didn't check your math, but extending the design isn't a safe thing to do unless you are planning to install a bypass. The build at the MHA workshop was slightly oversized because we had to make a couple of switches during the workshop. The design as it is represents what could be done, tolerance in the ISA figure would be in the order of 0.1m².
In short: the design is optimized already, going bigger might yield unpredictable results.

Nov 17, 2017 3:39:44 GMT -8 uga said:

For the top Cap I am planning to use silicate insulation board. What thickness should I chose my distributor has from 3 to 6cm thickness. Also what temperature should it be rated for? Is 1000C enough or should I chose the 1260 - 1400C rated material for the ceiling of the bell?

As I understand it, you are planning to make the top deck out of silicate board? Is that specificated to resist direct flame? If yes, take the thickest you can buy and the highest rated.

[uga]

Nov 17, 2017 6:45:55 GMT -8 Orange said:

I've heard calcium silicate boards are ok if they're not in direct contact with flame. I'm curious what climate do you have, any insulation under floor tiles?

I am the 2nd owner of this home. It was constructed with "Rockwool" laid in the concrete slab. Not sure if it helps since it's so compact.
I put a layer of 2mm cork on the bottom of the bottom of the Half barrel construction. But from what I learned from Peterberg post's is that wasn't needed.

[uga]

Nov 17, 2017 6:26:38 GMT -8 pinhead said:

An 8-inch batch box is a beast of a machine, indeed. It's scary how much heat an 8-inch batch box will produce. Honestly I'd run a 6 inch batch in that small space.

Based on the formula from Peterberg 's site in January we could use a 230mm Batch Box. Also, I would rather fire it less often, since small curious children are part of the equation.

[uga]

I didn't check your math, but extending the design isn't a safe thing to do unless you are planning to install a bypass. The build at the MHA workshop was slightly oversized because we had to make a couple of switches during the workshop. The design as it is represents what could be done, tolerance in the ISA figure would be in the order of 0.1m².
In short: the design is optimized already, going bigger might yield unpredictable results.

Thanks - I understand now.

As I understand it, you are planning to make the top deck out of silicate board? Is that specificated to resist direct flame? If yes, take the thickest you can buy and the highest rated.

The distributor says the silicate board is rated to resistance direct flame but I'll be conservative and use firebricks instead.

[uga]

Is it safe to use calcium silicate board as the heat riser?
Would this improve draft from a cold start?
Could someone please point me in the direction of the post which specifies the ISA of a Half barrel? I am really confused of how to calculate this for a semicircle.
What I would like to understand is how much ISA I will have available for a brick bell, (single skin laid on it's side - 6cm) without including a bypass.
For now, I have 3 half barrels and a span of a small gap totaling 272cm long.

My prototype smoked back until the heatriser (perlite and clay) was warm and there was a leak around the bottom of the barrel. But this was also not a true batch box with the proper primary and secondary air with a sealed door either.

[Orange]

from what I've read calcium silicate aren't good for the direct heat, only ceramic boards or maybe vermiculite. But clay and construction grade perlite should work fine too.

ISA of the half barrel is half circle width x length.