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Post by satamax on Mar 21, 2015 23:07:54 GMT -8
So, after reading though this thread, I got to thinking, what if instead of brick or cast slope to the floor, maybe a guy could use some, say, 4" strap steel with 3x1/2"channel iron welded on the underside to make a tube with wings protruding on either side, cross-sectionally. One of these on either side of the batch box to create your sloping floor. Then figure out a way to introduce the air maybe 2 inches or so ahead of the back wall of the firebox, either with a converging "bridge" tube, and single central channel, like what you've been using, or simply 2 separate pipes at the center of the hypotenuse of the right triangle of side wall-rear wall...Does that make sense? I'm planning to try it as soon as I have time, can anyone tell me why it obviously wouldn't work? This is excellent work, Matt. Thanks for sharing so freely. |
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Mar 22, 2015 2:06:17 GMT -8
Hey Andy, how are you finding the 716? Can you keep it running for an entire burn? Have had it running for 45 to 60 mins. |
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Post by talltuk on Mar 22, 2015 14:08:51 GMT -8
Ta mate
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Post by johndepew on Jan 29, 2016 18:26:00 GMT -8
I have a 'Walker Port' in my batch box, but the vertical tube only lasted maybe half the season before it burned up and disintegrated completely. I replaced it and the second one will need to be replaced at the end of the heating season. Is this pretty much a normal lifespan for these, or am I doing something wrong? The horizontal tube seems fine, but is not in the direct path of the flame at any point really.
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Post by matthewwalker on Jan 29, 2016 19:01:37 GMT -8
Hi John, I doubt you are doing anything wrong. I'm using heavy black pipe for the vertical section and getting a season out of them, but they are toast after that for sure. I am now just dropping new vertical sections in an oversized hole in the horizontal. I've achieved similar air delivery with all masonry arrangements, but the super heated, and quickly, secondary air is worth the yearly or bi-yearly replacement chore, in my opinion.
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Ralf
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Post by Ralf on Jan 29, 2016 23:58:50 GMT -8
Hi Matt & John,
did you think of or try using kiln shelf support columns from pottery supply for the Walker port ? They´re made of dense and hard "Cordierite" material which is able to withstand pottery firings up to 1300 °C / 2370 °F that last for hours or days while supporting the shelves for pots to be fired. Here in Germany they´re pretty cheap ( under 10 bucks a piece). Most useful: They´re hollow and a vertical slot for the secondary air release could be easily cut in the wall with an angle grinder or a tile saw. Standard dimensions here are: 43mm / 1,7" outer Diameter, 0.7" or 1" inner diameter, thinner-walled versions available, lenghts up to 300 mm / 11.8" . If you mount those in a connector at your bottom air supply tube degradation should be fixed. Only thing in question would be how they handle thermal shock, but since Coriderite has a very low expansion coefficient I think it´s worth a try.
I bought some of these myself, but committed to be well-behaved and finish my first-build standard j-tube first before starting wild experiments ;-)
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Post by matthewwalker on Jan 30, 2016 7:06:23 GMT -8
I'm not seeking an alternative, I am extremely satisfied with this design and all material choices. YMMV.
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Post by johndepew on Jan 30, 2016 18:28:50 GMT -8
Matt: That's pretty much what I thought. It's really no big deal to replace them. This time, I bought enough pipe for two, and went ahead and prepared them both, so I have a spare if this one fails over a cold weekend in March or something  It does make me incredulous when people start talking about all metal rockets... Ralph, that might work, but I need a minimum of 3.14 sq in of CSA in the void part of the tube. Do they make them that large? Honestly, I agree with Matt on this one, for my own personal use, but I am interested to see somebody else experiment with stuff like that. Keep us posted! |
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Ralf
New Member
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Post by Ralf on Jan 31, 2016 1:11:35 GMT -8
Hi, these ceramic tubes also come in 2.3 " / 6 cm outer diameter, I'm afraid the inner csa of these are a bit short of 3.14 sq in anyway. Good to see that your solutions work perfectly for you, just wanted the information to be up here in case somebody wants to try.
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Post by johndepew on Feb 5, 2016 17:54:00 GMT -8
Absolutely. I appreciate the information!
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Post by philippeelskens on Feb 15, 2016 13:45:38 GMT -8
Hi Matt & John, did you think of or try using kiln shelf support columns from pottery supply for the Walker port ? They´re made of dense and hard "Cordierite" material which is able to withstand pottery firings up to 1300 °C / 2370 °F that last for hours or days while supporting the shelves for pots to be fired. Here in Germany they´re pretty cheap ( under 10 bucks a piece). Most useful: They´re hollow and a vertical slot for the secondary air release could be easily cut in the wall with an angle grinder or a tile saw. Standard dimensions here are: 43mm / 1,7" outer Diameter, 0.7" or 1" inner diameter, thinner-walled versions available, lenghts up to 300 mm / 11.8" . If you mount those in a connector at your bottom air supply tube degradation should be fixed. Only thing in question would be how they handle thermal shock, but since Coriderite has a very low expansion coefficient I think it´s worth a try. I bought some of these myself, but committed to be well-behaved and finish my first-build standard j-tube first before starting wild experiments ;-) Hi Ralf, I would be interested in trying this material! Could you give me some information where I could buy these? I live in Belgium, so if you order them online, I might be able to use the same supplier! Thanks! |
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Ralf
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Post by Ralf on Feb 19, 2016 11:53:38 GMT -8
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Deleted
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Post by Deleted on Feb 20, 2016 5:04:53 GMT -8
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Ralf
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Post by Ralf on Nov 23, 2016 5:09:00 GMT -8
Hi, I´ve got a few questions concerning the specific pre-port secondary air supply in Peter van den Berg´s newest design shown here.It´s a floor channel with a vertical pre-port tube opening half way up the port. Peter states that this configuration produces the best results when fired "upside down", starting the fire at the top of the fuel close to the back. I read many times that it´s crucial to preheat the secondary air well before injection in the burn path. How does this happen here if the fire starts at the top, heat will rise but the bottom air supply channel is well shielded under the fuel pile ? I´m just asking about the start of the burn until all the fuel is on fire. And how long does it take until the fuel is completely lit with this lighting method ? Could this channel better be heated right from the start by flipping it upside down and feeding it from a tube running through the ceiling (as the p-channel does) ? I´m aware that this design makes the build and exchange of the pre-port super-easy, and that my proposal would re-complicate it. Would the possible benefit be worth it ? Thanks for clarifying ! All the best, Ralf PS: I also discovered this "upside down" firing method in an advice link given by a local oven builder for best practice in a "standard" woodstove (here the fire´s lit close to the front as opposed to the batch box). Audio is in German with funny Swiss words mixed in, but when you watch you´ll get the idea. Light at the top, keep air supply fully open throughout and you have a smokeless burn (possibly unburnt hydrocarbons not adressed). |
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Post by peterberg on Nov 23, 2016 6:01:27 GMT -8
It is simple, really. When a small pile is lit, some air is going over the fuel and reaching the port this way. This is sufficient as secundary air, so when you scale that up to a small fire on top of a big pile that would be more or less the same situation. The p-channel or floor channel supply is needed when the fire is ramping up to the top of the burn, by that time the floor- or p-channel is heating up sufficiently. In practise, I found the method the empirical way first and reasoned the why afterwards. So I could be wrong in the why but the measured results won't lie, hopefully.  In normal operation, time from kindling to full burn is between 15 and 25 minutes. Influenced by size of logs, species of fuel, moisture content, quality of chimney stack and wind velocity. |
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It does make me incredulous when people start talking about all metal rockets...
