Re: Starting new 36" build
Dennis
Great job.
Tracy
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Re: Starting new 36" build
That looks fantastic Dennis - I know you said this isn't a race but I think someone just flashed past me on the finishing straight. I really hope that buttress is over engineering because it never even occurred to me that my entry arch would need buttressing. Hard to resist lighting a few fires in there I'd say, but take your time - the longer the mortar has to cure the better.
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Re: Starting new 36" build
Lots-o-progress this weekend: Entry arch completed and buttressed (is that a verb?); flue completed and chimney fitted; huge mess is backyard mostly put in garbage bags.
Right now I am curing with a worklamp, but it only gets up to ~100 degrees. Think I will borrow Tu's idea and use Chafing fuel for the next stage of the cure.
Just need to get the soapstone & stainless tubing for the entry, and refractory caulk for the heatbreak this week and the oven will be complete.
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Re: Starting new 36" build
Originally posted by GianniFocaccia View PostNo direct experience, but since that post I observed a video somewhere showing a worker bonding multiple yard-long 'columns' of IFB that ended up making a very rigid sheet of material. I also discovered there is such a thing as IFB mortar, so the sky's the limit.
BNZ Materials | Insulating Fire Brick
The arch is free standing from my dome, and I have about 2 inches of insulation that extends beyond the edge of my arch on each side. For the buttress, I mortared 2 IFB to each side of my arch over the insulation. Then I am going to mortar a 8" x 8" cinderblock to that firebrick and to the concrete hearth . That way, my arch is effectively buttressed to the concrete base, but there is a layer of IFB between the arch and the cold concrete that should keep it from losing too much heat into the base.
Since my entry arch is already isolated from the dome, I wasn't too worried about finding a perfect solution - but thought this was better than using a more heat conductive material for the buttress.
I also thought that if the mortar connecting the IFB and the arch doesn't hold, there should still be sufficient tension between the arch and the cinder block that it will serve it's purpose.
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Re: Starting new 36" build
Update: We are experiencing a phenomenon known locally as "June-uary". It's cold and rainy, which means I have not been able to make any progress on my vent arch.
So that has given me lots of time to think about my approach, and to focus on identifying sources for what remaining supplies I need. Here's what I have decided to do:
Heat break
+ At the back (dome side) I have about a 1/2 inch gap between the vent arch and the dome arch. I am going to stuff that with a 3/4" length of ceramic fiber twisted braid - typically used as kiln gasket. This won't be exposed to any flame, so it should be ok
+ Inside the arch, There is about a 1/4" gap between the dome arch and the vent arch. I am going to fill that with Kaowool moldable. It looks like it should easily handle the temps - and since I have a relatively narrow/deep slot - I don't think it will ever work its way out once it is in there.
Entry floor
+ For the break between the oven floor and the vent floor, I decided to go with a piece of 0.5" x 1.5" Stainless rectangle tubing. I am going to cut the bottom of it away, except for at the two ends. It will basically be a channel, except I'll leave about a half inch of material at each end so that will sit level. I found a supplier for this right down the street, so decided to stop shopping!
+ For the entry floor itself, I found an installer with scraps of soapstone from whom I can get a piece cut to fit. I figure it will probably be 2 cm thick
+ Under the soapstone, I am planning to use IFB splits. I am still debating this, but I don't really see any benefit to using firebrick. I don't need the entry floor to be hot, and I want less mass to pull heat out of the oven. Plus, the IFB is easier to cut to exactly the height I want, less prone to crumbling/breakage, and I already bought it
Enclosure
+ I am going with the "doghouse" style. I really like the dimensions of Smuth10's oven - so am going to sketchup something like that for the roof pitch and height.
+ I've decided to use cultured ledgestone drystack (lick and stick) for the bottom, and stucco the top. I will probably also do a faux chimney detail in the front to break up the space
+ I'm going to use trim stone that matches the drystack for the decorative arch
+ the roof will be standard tab to that matches my house
+ I plan on pouring a concrete counter at the level of the oven entry
Chimney
+ I already purchased 8" Duravent anchor + 24" stainless pipe + cap.
+ I plan to build a chase for it and cover with the same material as the base
+ Duravent has standard chase covers available for their dual wall, so that is going to dictate the dimensions of my chase
+ I went with the chase vs. having the stainless go through the peak for both aesthetic and cost reasons. Through the peak flashing for round pipe is very pricey, and I don't really like the way it looks.
Lots more work to do, that is for sure! I would love any feedback on my plan. I didn't mention stuff like dome insulation - but it's on my checklist too.
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Re: Starting new 36" build
On the IFB - I saw a comment you made a while back suggesting that it might be tough to get the mortar to stick to it. Do you have any more background on that issue?
BNZ Materials | Insulating Fire Brick
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Re: Starting new 36" build
Originally posted by GianniFocaccia View PostDennis,
I've seen this question asked previously, and seem to remember that caulk is not considered a viable long-term solution. Installation and price advantages aside, I don't see why it couldn't be used to 'seal' a piece of ceramic rope on the back side. I think for applications the size of ours, rope cost isn't prohibitive as long as one can purchase just the length needed.
As far as your idea to use IFB on the back of the thermal break, I like it. It's inexpensive, easy to cut and readily available.
John
I was reading through old threads and I saw comments about high-temp silicone caulk not being suitable for long-term heat exposure but don't recall seeing any specific comments about this refractory stuff. It seems to be the same insulating materials as the rope and board - just in a different medium
But you are right, the rope isn't too spendy. It was more that I thought caulk might give a better seal - but it sounds like it is more like a putty than a caulk so maybe not.
On the IFB - I saw a comment you made a while back suggesting that it might be tough to get the mortar to stick to it. Do you have any more background on that issue?
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Re: Starting new 36" build
Dennis,
I've seen this question asked previously, and seem to remember that caulk is not considered a viable long-term solution. Installation and price advantages aside, I don't see why it couldn't be used to 'seal' a piece of ceramic rope on the back side. I think for applications the size of ours, rope cost isn't prohibitive as long as one can purchase just the length needed.
As far as your idea to use IFB on the back of the thermal break, I like it. It's inexpensive, easy to cut and readily available.
John
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Re: Starting new 36" build
You could make SS channel by cutting the bottom away from SS tube with angle grinder?
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Re: Starting new 36" build
Amac - Thanks. I understand now
Russell - good thought - although the cost of the tubing seems to be in the $10-15 range so I am not sure how much work I want to do to find it!
Question for the crowd -
Refractory caulk - anyone used this as a sealer for a thermal break? Seems like it could do a better job of keeping the smoke in the right place than Ceramic Fiber rope; Has low thermal conductivity (basically same composition as CF board); would be easier to install; and is pretty cheap to boot
Kaowool Caulk Details
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Re: Starting new 36" build
Deejayoh,
Another option for a source of SS channel are businesses that repair or salvage old resturant equipment or medical equipment. Alot of this equipment is high grade 316 SS. I was able to get a 3' x 6' sheet of SS for scrap prices from an old autoclave unit (for my oven door eventually) and 1"X2" tube (hearth thermal break) from a resturant prep table that was headed to the scrap yard (see pic). I guess you have to determine if it is worth your time. But for me, that is half the fun to see what I can get to build my oven with recycled materials. I did snitch the thermal break idea from GianniF though.
Russell
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Re: Starting new 36" build
Air is only 1/60th as thermally conductive as fire brick. So even if it is not the best solution, I thought it should still pretty radically reduce the heat transfer.
To quote wikipedia - the fount of all knowledge (my emphasis)
Air and other gases are generally good insulators, in the absence of convection. Therefore, many insulating materials function simply by having a large number of gas-filled pockets which prevent large-scale convection.
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Re: Starting new 36" build
John - thanks for weighing in. I know you have been thinking a lot about this!
Borrowing, yeah - that's it!
I agree with you on the use of the channel. Seems like the way to go - I just haven't been able to find stainless channel - and stainless tubing looked better than carbon steel channel in terms of heat conductivity. But thanks for the lead on Phillips. I will give them a call.
As for the heat break - did my comment about using the IFB to tie the arch to the dome make sense? I think I need to do a sketchup, but my skills are failing me there. I'll try to post something later
Dennis
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Re: Starting new 36" build
I'm planning to incorporate/steal a couple of your ideas for the entry: a soapstone floor (sourcing a scrap now); A heat break around the inner arch; and a metal divider between the vent floor and oven floor (still looking for this)
First off, I sourced a piece of 316 stainless plate from a supplier in my territory and was subsequently told that heat will eventually cause this to warp. I'm not convinced of this because the flow of air at the entry floor goes into the oven, not out, and because of the sheer number of mobile ovens with this feature.
So after learning this, I am strongly considering going back to the soapstone entryway, primarily because of the complaints of the staining of firebricks.
Secondly, rather than cut a piece of square stainless tube lengthwise, you can buy a piece of channel, which is three sides of a square tube. I too considered this, but believe the optimal bridge is a full tube separating two masonry materials with beveled edges. The bottom wall of a square tube has no contact thus the thermal transfer is limited to only the top-most points of contact, which, despite it's 12x thermal conductivity, is basically the thickness of the tube, 1/8" or so.
Regarding a heat break and the strength of a standalone entry arch, I plan to move ahead with my original plan, which is similar to yours. I will incorporate some kind of buttressing, including suspending my flue so that it too, is separate from the entryway and doesn't weigh on the arch itself.
Anticipating my eventual need for a stainless vendor for a door, six months ago I approached a stainless steel fabricating company in my territory (I'm in outside sales) who last week called me in and may become a client. I think they have stock stainless channel as well as tube, plate and bar steel of all kinds and sizes. You can find them here:
Phillips Steel Company - Established 1915 - Long Beach, CA
Hope this helps,
John
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Re: Starting new 36" build
Amac - Yeah, I understand there is a vacuum - which has zero thermal conductivity. What I was thinking is that on that list, Air is only 1/60th as thermally conductive as fire brick. So even if it is not the best solution, I thought it should still pretty radically reduce the heat transfer.
But I guess what I am missing is that I add another material into the tube - I am essentially adding yet another plane through which the heat has to transfer which will be even more effective. I have some leftover bits of FB board that I can trim down and feed into the pipe (and probably put under it). That should work pretty well.
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