Hi Everyone, started my first 6" batch box this week for a friend in his newly constructed strawbale house. It is replacing a potbelly stove and is going to be piped through a bench. Thought I would share and get some advice on anything that might stand out and I'm missing. My experience has been with 8" stoves and i've never done anything smaller. The dimensions are based on Peter's designs, with a few minor alterations to provide for easy brick laying.
1) box dimensions are slightly altered by .5" height and width which I assumed would not be an issue.
2) the port I left at a two brick height which is 9" instead of the recommended 9.5". I increased the width by an 1/8th of an inch to make up for the missing area. I figured that this might decrease the efficiency of the overall burn, but not be too much of a detriment to the actual working of the stove.
3) The space for the bench was somewhat smaller than I would have liked, the friend was a little hesitant to build a "bell" for the bench and preferred the long tested piping method of a traditional rmh instead. The bench is 10 feet long, so a total of 30ft for the piping including the bends at 5' each. He has a very long exposed chimney pipe rising up next to where the barrel is going to be and up through the house, probably 15 feet, so I feel like this thing is going to really get going when lit up.
Anything you've experienced with a 6 inch that would be helpful? Thanks.
I was going to wait till later to respond as I'm working on my new 6" batch.
But the more I thought about it I wanted to toss a few ideas out for your consideration.
I wanted to strongly suggest using 8" pipe inside the mass. It will not effect flow and it leaves options open for later.
I am assuming the house already had a 6" chimney pipe and the owner would like to keep it. If Not make it 8" all the way thru the roof.
Remember to use cheap long lengths of HVAC pipe inside the mass.
One last recommendation is skip the 180 pipe turn and make a small brick box (don't call it a bell) pipe in , pipe out and a cleanout tee placed to access both horizontal pipes.
I'm guessing your photo is a mock up? The secondary air tube should be level with the floor.
It is indeed a six inch because the chimney was already installed. Originally I had thought an 8" would be better, as it would do a better job at heating the house. However, the owner has radiant floor installed too and therefore a big wood heater will most likely not be that necessary so 6" it is. I like the idea of doing a brick bell at the end of the bench and will see about doing that as he has some extra brick laying about that would function well for that.
The P-channel is going to run along the top of the box, though I know the floor channels are popular I haven't done it that way previously and was somewhat chicken to change anything from the success I have had on my stoves with someone else's.
I did exactly the same as you where I maximized the bricks more and leaving out the cutting for a minor change in dimensions. Although I don't have a Testo gas analyzer to verify how much this has affected the performance, a half season of successful use has proven that it burns clean enough for me and runs just fine.
My 6" batch box conversion thread shows my brick layout as I was gluing them together here
Secondary air from the top will work just fine, its just much harder to replace when it craps out which was one of the reasons why it was brought down to the floor. Preheating the secondary air before it gets introduced to the fire and acting as an end iron to keep wood from blocking the port are two other perks the floor channel gives.
EDIT: BTW.... Those angled floor bricks were added to Peters design to help pool the coals together so that they would burn up more for the one fire he often does a day. Matt Walker has said though he leaves them out in his design because he does multiple loads a day and also makes it easier to clean. I have removed mine as I often do more than one burn a day and don't need this feature. No problem either way, but just thought you might like to consider it.
See Stove Chat 14 at 39:25 where Matt discusses this.
Thanks Gerry, that is a very good thread. I hadn't read through that one, but there was some great information there.
I am going to put the angled floor bricks in, I did in my 8" batch, and they do seem to roll the coals into the center.
I've been running mine for two years and haven't seen any signs of wear on the Pchannel, most likely since the secondary air is cooling it. Only time will tell though. I'm going to build another 6 inch in my woodshop next year and I will give the floor channel a go just so I have a bit more experience with the design and easy replacement in the future if it is necessary.