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Post by pinhead on Jan 29, 2015 13:26:58 GMT -8
Love it! This is the type of build I get excited about - easy to source, affordable materials, optimized system, DIY potential. When do we get to see it in action? Will the secondary air intake have any adjustment? On a tangent - I will be building something along these lines and am wondering about building an insulated oven on top of the burn box. I suspect it would be better for efficiency if I just insulated it, but if I'm not too concerned about super high efficiency, and getting every last bit of heat further down the system, do you guys think this would be advisable? (sorry to hijack the thread) And Pinhead, you might suggest to your girlfriend that she could start a support group for Spouses and Significant Others of Guys Addicted to Rocket Stoves and Heaters (SSOGARSH). If I don't get the top capped off tonight (unlikely) it'll be this weekend; I still have to build the heat riser and mix a lot of mud for the top of the whole thing. The secondary air has no adjustment at the moment, though it would be easy to add it later on if needed - for warmup, etc. I don't think a batch box needs the firebox insulated at all, IIRC. I had the same crazy idea as you as I was drying the thing out the other day - the top got pretty hot pretty quickly. I'd keep it simple and make a "dome," made out of radiant barrier insulation, to put over whatever is to be cooked/heated. If anything, that would help the stove heat up more quickly, as it keeps the heat from radiating upwards away from the roof of the stove. And she's the first girl I've ever met that's interested in this sort of thing who is also attractive and kinda-sorta likes me, too. ** Winning **
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Post by pigfarmer on Jan 30, 2015 3:03:53 GMT -8
Hi I'm a newbie and I was wondering if those bricks will hold up over time as the wall of the batch box instead of using fire brick . Or are you just using what you have access to and waiting too see how long they last ?
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Post by pinhead on Jan 30, 2015 6:56:11 GMT -8
Hi I'm a newbie and I was wondering if those bricks will hold up over time as the wall of the batch box instead of using fire brick . Or are you just using what you have access to and waiting too see how long they last ? We tore down an old brick building and was told I could have all the brick I wanted so I grabbed as much as I could load up. The body of the batch box doesn't get as hot as the heat riser or the burn chamber of a j-tube so I suspect (hope) they'll stand up over time. I'm going to encase the batch box with cob just in case, though.
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Post by belgiangulch on Jan 30, 2015 7:26:41 GMT -8
Hi Pinhead; This is just awesome! exactly what I had in mind for my leaky shop. How big a space is it in ? How long is the mass ? Piping or half barrels ? More pics please. By the way sounds like quite the girl you have run across, A rare find indeed ! congrats.
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Post by pinhead on Jan 30, 2015 8:14:35 GMT -8
Hi Pinhead; This is just awesome! exactly what I had in mind for my leaky shop. How big a space is it in ? How long is the mass ? Piping or half barrels ? More pics please. By the way sounds like quite the girl you have run across, A rare find indeed ! congrats. Thanks for the compliment and, yes, definitely a rare catch! The mass is two half barrels, divided with a brick wall making two separate bell chambers. She helped me build it over a weekend back in November. If my calculations are correct, we use a little over a ton of clay/sand in the mass. We'll probably add more, depending on how much heat capacity we're wasting with such a big stove in such a small shop. The shop is probably 15' x 20' - maybe a bit smaller. Limestone with no insulation. I installed a radiant barrier on the ceiling (roof) which made a huge difference. The building has been standing for 100 years with no gutters so the foundation is getting soft and the east wall is starting to fall out. She and I replaced one rock that fell off the top level and sealed everything back up using the clay/ash/sand mortar that we're using on the stove. When there's a north wind I can still feel a cold breeze blowing through some of the cracks so we'll probably spend some time with this mortar filling those, too. If we wanted to really go crazy we'd face the inside walls with clay/ash/sand but I don't think with this huge stove that will be really necessary.
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Post by pinhead on Feb 2, 2015 6:14:34 GMT -8
We got it finished this weekend. The door is from a barrel stove kit and is a bit smaller than I had hoped; we had to build a frame around it which blocks off the bottom three inches or so of the firebox. The frame is made out of square tubing that sits flush against the brick. I tack-welded the top of the frame to the angle-iron that supports the roof. This picture doesn't show it, but I filled the gap at the bottom with clay-sand-ash. To attach the door to the frame, I drilled bolt-sized holes in the front and on the back side I drilled holes big enough to fit a socket. The primary air intake on the stove door isn't large enough so I had to carve an airway directly beneath the door. Unfortunately it seems the combination of a large barrel and double-bell bench is too much heat extraction for my situation; after burning the stove yesterday for roughly 8 hours the exhaust temperature finally reached 105°F according to my infrared thermometer. The mass started at 55°F, having been warmed up from a fire on Saturday. On the other hand, it kept the shop plenty warm and there was no visual smoke with only a slight sweet smoke smell mixed in with the steam. It definitely burns cleaner than any other wood stove I've personally seen.
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Post by pinhead on Feb 2, 2015 7:24:02 GMT -8
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Post by matthewwalker on Feb 2, 2015 8:32:46 GMT -8
Nice work there! You might be able to simply adjust bell size by bringing up that chimney stub a little bit. You could improve stack temp and draft significantly with a small change, and if you leave it adjustable you could stuff it down there once things were hot and flowing well. Or perhaps plumb a bypass that does the same thing. Still, if it lit off at 55 and had draft, you are probably doing great. Once it's all dry it will warm up and flow a lot better I'm sure. Great update, it's fun to follow along with you on this one.
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Post by pinhead on Feb 2, 2015 10:05:13 GMT -8
Nice work there! You might be able to simply adjust bell size by bringing up that chimney stub a little bit. You could improve stack temp and draft significantly with a small change, and if you leave it adjustable you could stuff it down there once things were hot and flowing well. Or perhaps plumb a bypass that does the same thing. Still, if it lit off at 55 and had draft, you are probably doing great. Once it's all dry it will warm up and flow a lot better I'm sure. Great update, it's fun to follow along with you on this one. Thanks! By "chimney stub" I assume you mean the transition from the second bell to the base of the chimney. I don't know why I didn't think of that; I was kind of planning on knocking out the dividing wall between the two bells to make the bench a single bell. I do like the idea of raising the exit, especially since it would only require me to tear down the very end of the bell instead of half of the thing. I'm going to spend some time contemplating how, exactly, to build an adjustable bypass. Should I be able to run this stove with the door open? My [possibly unfounded] complaint is, when I open the door to add another log, the room gets filled with smoke. Then again, maybe I'm complaining about nothing.
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Post by matthewwalker on Feb 2, 2015 10:40:22 GMT -8
No, you need a door for sure. That's not a flaw in yours, it just is. As you get into these lower air set-ups (I ran an S portal for a couple weeks before the pre port tube) the door and it's sealing get way more critical. The original design is just going flat out, these are a little bit choked so need good seal and proper inlets and such to really work well. I do a simple external bypass by plumbing in the two exits externally, and use a damper on the shortcut. So, a chimney where yours is now from up high in the bell, and one plumbed in down low next to it. Join them just above the bench with a T and put a damper in the high exit. Done, and constantly variable so you can get good flow in all conditions. With a second damper you can stop flow when the stove is out, which probably doesn't matter to you in this build. Here's an example of that sort of bypass. Room will be tight in the halves, but I think you can get it.
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Post by pinhead on Feb 2, 2015 14:03:43 GMT -8
I was thinking of something along those lines, as well. Like you said, though, it'll be tight inside the half-barrel.
I'm not sure I mentioned it or not so I think I should clarify: The two half-barrels are separated by a wall to form two bells.
Do you suspect the temperature differential between the roof and the floor of the second bell would be high enough to warrant such a modification? The height difference, after all, is fairly minimal - at around 11 inches from the floor to the peak of the arch.
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Post by matthewwalker on Feb 2, 2015 16:08:11 GMT -8
Oh, yeah, I see....no, probably not. Just lift the exhaust to where it runs well the way you typically use it, and call it good. That's probably what I would do.
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Post by pinhead on Feb 3, 2015 8:21:07 GMT -8
After burning a good bit of wood yesterday, I'm not sure I really have anything to complain about.
I burned some well-seasoned wood yesterday and lit the stove a little differently than I have in the past.
I lit a good fist-full of twigs/kindling, just in front of the throat of the stove. Once all of the kindling was consumed in flame - and before it burned down to coals, I put another two hand-fulls of longer small-diameter sticks over the top of the flame, extending towards the front of the firebox. Once those started smoking/crackling, I loaded seasoned three 3-inch diameter logs, then two bigger logs as I can fit them over the top, filling the firebox to the roof.
The couple of hand-fulls of twigs directed the smoke into the heat riser and kept the bigger stuff from smothering the small fire.
This procedure seemed to work very well, as I didn't have to tend the fire at all. The low air setting with the S-Portal and low exhaust temps combined with the relatively big logs seem to make this stove burn cleanly for quite a long time.
I lit the fire at about 6pm and had good heat about 15 minutes later. The fire was "coaling" at around 9pm, at which time I added a single 8-inch diameter log, completely filling the firebox (on top of the coals). I went to the house shortly thereafter and don't know how long it burned, but when I checked it this morning, everything had burned down to ash, and the shop was still very warm.
Outside temperature was about 15°F and breezy.
During the burn, I "checked" the quality of the exhaust visually and with my sniffer. I could smell smoke during the first 15 minutes, as the large logs were having a little trouble lighting. As soon as I could hear the roar of flame reaching into the heat riser, I went back out to check the exhaust. It had turned to steam and had no "smoke" smell - all I could detect was the "sweet" smell of clean, steamy exhaust. The outlet of the chimney resembled the outlet of a clothes dryer on a cold day.
I think next time I'll load the entire firebox with either small splits or thumb-sized sticks to see how quickly the firebox will come up to temp with smaller wood. Once the small stuff burns down I can easily add larger logs.
The experimentation continues.
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Post by ericvw on Feb 3, 2015 15:55:30 GMT -8
pinhead, Sounds like you're getting your stove dialed in pretty quickly! Liking all the pics- a great start to finish build thread.... Well done, sir! Eric VW
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arlyn
New Member
Posts: 4
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Post by arlyn on Feb 3, 2015 16:12:16 GMT -8
I've found that toilet paper tubes, drizzled with a little candle wax, can get a fair sized bunch of kindling (also drizzled with a little wax) to take off nicely. If there's a little remnant of TP on the tube, so much the better as the "fuse".
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