6" ceramic riser or 8" system

My current system in the living room is a 6" pebble style with a standard firebrick core and it works good, heating my house (1060 square foot) and life is good. However it takes a four hour burn to get things up to "happy mode". I average 400 on top of drum and I believe that I would like to be at 600. Should I put a ceramic heat riser on or skip that and go for an 8" system?

My guess is your core is not doing what it should. The test I saw on Brian Cobb's got the barrel top to 790 in under 45 minutes.... rebuild the riser and core with insulation fire bricks and try again

Careful Jon, If you're talking about brian's build, that you just saw. It's a batch. Far more powerful than a J.

Jonathan, you are talking about a J?

Tho, Jon's suggestion to redo the whole core is a good one. Insulating firebricks for the back of the J and heat riser. Ans heavy firebrick splits in the feed. Insulated from outside.

Satamax Antone wrote:Careful Jon, If you're talking about brian's build, that you just saw. It's a batch. Far more powerful than a J.

Jonathan, you are talking about a J?

Tho, Jon's suggestion to redo the whole core is a good one. Insulating firebricks for the back of the J and heat riser. Ans heavy firebrick splits in the feed. Insulated from outside.

Appreciate the correction on this. I forgot the difference between a smaller j burning vs a batch

I vote you build an 8", my barrel top runs 800-900 F consistently in about 30 minutes.  Like max said insulated bricks in burn tunnel , splits in feed tube and I prefer the matt walker cast riser over brick riser.

I built the 6"j tube from the builders guide and believe me it has been insulated exactly as a firebrick core should be. Still I wonder what kind of a gain would occur with a ceramic riser? Something like 10% maybe?

jonathan kedzierski wrote:I built the 6"j tube from the builders guide and believe me it has been insulated exactly as a firebrick core should be. Still I wonder what kind of a gain would occur with a ceramic riser? Something like 10% maybe?

In the heat riser, the enemy is mass. So even if insulated properly, your bricks will take an hour or more to reach the "nice" operating temp.

But what you say about your "happy mode" taking 4 hours to reach, makes me think there might be something else. Draft for example. Another thing about the barrel temp, it's dependent on power of the core, but also a great deal, on the barrel gap on top of the heat riser. The closer the gap, the hotter the spot. Tho, after a point, the stove stalls. If you have a barrel lid, and your gap is big, you could temporarily lengthen the heat riser with some sheet metal held by wire.

Satamax Antone wrote:

jonathan kedzierski wrote:I built the 6"j tube from the builders guide and believe me it has been insulated exactly as a firebrick core should be. Still I wonder what kind of a gain would occur with a ceramic riser? Something like 10% maybe?

In the heat riser, the enemy is mass. So even if insulated properly, your bricks will take an hour or more to reach the "nice" operating temp.

But what you say about your "happy mode" taking 4 hours to reach, makes me think there might be something else. Draft for example. Another thing about the barrel temp, it's dependent on power of the core, but also a great deal, on the barrel gap on top of the heat riser. The closer the gap, the hotter the spot. Tho, after a point, the stove stalls. If you have a barrel lid, and your gap is big, you could temporarily lengthen the heat riser with some sheet metal held by wire.

happy mode being the house is 75 degrees. I imagine the riser currently takes about 45 mins to fully heat up.

Well, Jonathan, if you want more advice than this. I think it's time to get the pics of the build out!

She seems perdy drafty 😀

Pulled the drum off and found I could add an inch to the length of the riser, bringing the gap to 1.5". Loaded the wood feed up with some ash (fuel) and bingo!

So based on this, correcting an overly large top gap seemed to get the power desired by your 6" system?
I'm curious as I'm not sure if I want to build a j or batch....either seems like a good deal with batch having advantage of bigger pieces of wood and more heat output faster but slightly more fussy design

John, the heater isn't more powerful just by restricting the gap. The top of the barrel's getting hotter, that's all. Logical, because the riser is closer to it now, good for cooking on top.

Peter van den Berg wrote:John, the heater isn't more powerful just by restricting the gap. The top of the barrel's getting hotter, that's all. Logical, because the riser is closer to it now, good for cooking on top.

So does that mean more heat to barrel but less available for the mass to absorb?

Jon McLain wrote:

Peter van den Berg wrote:John, the heater isn't more powerful just by restricting the gap. The top of the barrel's getting hotter, that's all. Logical, because the riser is closer to it now, good for cooking on top.

So does that mean more heat to barrel but less available for the mass to absorb?

Yes. And that's the very hard bit, to master. Ratio of direct heat to stored heat in any masonry heater.

I did lose about 10-20 degrees at the pipe going into the mass but I like to keep a large water pot on top of the barrel to help humidity the house, maybe now I won't be getting shocked as much when using the vacuum cleaner 😃

Peter van den Berg wrote:John, the heater isn't more powerful just by restricting the gap. The top of the barrel's getting hotter, that's all. Logical, because the riser is closer to it now, good for cooking on top.

I would like to point out that Peter van den Berg!!! Replied to a post that I started!! With that said... It acts more like a wood stove, more heat from the drum , room heats up faster and less heat down in the mass.

Granite top arrived today!