Barrel Vault in So. Cal.

[WJW]

Re: Barrel Vault in So. Cal.

Making progress on the chimney arch and transition from vault to chimney arch.

More than one way to skin a cat. I used bungies to keep pressure on the bricks as they cure. I had them supported from underneath and alternated sides working toward the center. Pop the bungie off to lay the next brick, after the brick is on, stretch the bungie a bit and pop it over the brick. Repeat. Seemed to work well and put a lot of pressure on the bricks as they cured. I did all but the keystone that way. After the arch bricks had cured for a few days with the bungies, I removed them and did the keystone.









If anyone sees anything that rings alarm bells, please speak up.

Bill

[Tscarborough]

Re: Barrel Vault in So. Cal.

Do you really want to hear it?

[Les]

Re: Barrel Vault in So. Cal.

If anyone sees anything that rings alarm bells, please speak up.

Bill, it's good to go outside of the box but I think this might be a stretch (pun intended). Why wouldn't you use a form? It's easy to set the brick at your leisure and allows the brick to set. What I see is cracks and slipping bricks because of the low arch. I really hope I am wrong. I don't mean to be harsh but that is my honest opinion.

[WJW]

Re: Barrel Vault in So. Cal.

Yes...I want to hear it. (Gulp)...Hell of a lot easier to fix it now than after I have all the stucco and insulation on...At this point it'd be a relatively easy matter to redo the arch. After I tie it altogether...not so much.

If the consensus is that I've screwed things up, I'll break out the angle grinder and cut up that arch in a New York minute. (That's the beauty of knowing you don't know what the hell you're doing...low expectations and very little ego to get in the way. Before I started this oven I'd never buttered a single brick in my entire life...I'll be okay if someone tells me I've FUBAR'ed the arch.)

Truth be told, I was worried about the low arch too. I pushed down on it really hard yesterday and it seemed to hold fine and didn't crack. That being said, it hasn't gotten hot yet. That's why I held off on mortaring the transition from vault arch to chimney until I heard some feedback.

Fire away. (no pun intended)

Bill

[Tscarborough]

Re: Barrel Vault in So. Cal.

The arch is fine, low, but it will hold. The throat pieces look to be too thin, though. That is the absolute hottest part of the oven.

[WJW]

Re: Barrel Vault in So. Cal.

Well hell...that's a relief it's not unanimous about the arch. The throat pieces are just sitting there for the photo and not mortared in place.

But they are very thin...I cut the bricks in half diagonally so that the thinnest edge is like a quarter inch thick.

I was planning to inset that thinnest portion into a line of quarter length/half thickness brick (2.25x1.25x4.5 inch) mortared on the top of the chimney arch in the intierior of the throat... so the very thinnest portion of the throat bricks weren't going to be exposed to direct heat...but there's no doubt that about four inches of brick that will be exposed to flame will be less than a inch and a quarter thick. I didn't realize that the throat got so hot, although it certainly makes sense now that I think about it.

Easy fix on the throat pieces...I'll dump the ones I cut thin and do something with the full thickness of the brick (2.5 inches) in the throat.

I thought you guys were both going to be saying to cut that arch out. I was trying for a low arch, but it ended up a bit lower than I had planned. Glad to hear Tom thinks it will hold.

Les,

If the arch is holding now with me pushing down with....say seventy-five pounds of pressure...do you think it will continue to hold? Or do you think it's just too low to maintain its strength after repeated firings?


Bill

[Tscarborough]

Re: Barrel Vault in So. Cal.

It will hold as long as you have enough buttress, and it appears you do. The weakness will be the fact that if the mortar goes, then the arch goes.

[Les]

Re: Barrel Vault in So. Cal.

Les,

If the arch is holding now with me pushing down with....say seventy-five pounds of pressure...do you think it will continue to hold? Or do you think it's just too low to maintain its strength after repeated firings?


Bill

I honestly don't know. There was someone a while back that had about the same scenario as you. The topic was how he could get a brick that was sliding out, back in. That was the reason I questioned it - it looked familiar.

[WJW]

Re: Barrel Vault in So. Cal.

I appreciate the feedback and constructive criticism. I changed out the throat pieces to use full thickness bricks (2.5 inches). I left the arch as it was because cutting it up would have been a hassle, I'm optimistic by nature, and I pressed darn hard on it and it seemed rock solid to me.

Some pics...

Testing the arch for a bit of piece of mind....



It's a safe bet that I can't fit inside this thing. Dressing the joints of the throat.


Close to closing it up

[brickie in oz]

Re: Barrel Vault in So. Cal.

It's a safe bet that I can't fit inside this thing.

Cut up into nice joints you would though.....

[WJW]

Re: Barrel Vault in So. Cal.

I had heard there were cannibals in the south Pacific but I had no idea there were any in Oz.



Bill

[WJW]

Re: Barrel Vault in So. Cal.

More progress today...

I ordered a stainless steel, double walled chimney. 48 inches long with an eight inch diameter.

I also received my temp managment stuff today as well. Four thermocouples and an infrared thermometer which will accept data input from the thermocouples. Additionally, the thermometer will data log one hundred values..and also has a USB port and cable which allows it to download data to a lap top in real time. Should be very easy to profile the heat saturation and cooling profile/timeline. Can't wait to profile it as built, and then put a temporary extra layer of firebrick on the oven floor to see how it heats up/retains heat with a double layer of fire brick on the floor.

Here are the latest pics

The oven is closed and I'm working on the entry



My "heat management hardware"

[couchpotatoe]

Re: Barrel Vault in So. Cal.

Hi All,
I've finished the stand for my barrel vault that will be built along the lines of Perk1018's - but with a traditional exterior flue and chimney. I'd like to know the best way of installing the thermocouples. Do you simply drill down to the depth you want to read from the outside of the completed oven? Do the holes have to be lined with anything if twisted, bare 24 gauge thermocouple wire is used - or are the firebricks effectively an electrical insulator?

Has anyone installed multiple thermocouples and a rotary double pole switch in a box with its own thermocouple for a reference temperature? I'm looking to do multiple measuring points and am trying to save a dime or so )

Thanks for any feedback.

Russ

[WJW]

Re: Barrel Vault in So. Cal.

I'd love to help but I don't know the answers to your questions. I purchased ceramic fiber insulated, high-temp thermocouples. I plan to place my four thermo couples as follows:
1. In the center of the hearth brick approximately 1/2 inch below the surface of the hearth.
2. In the center of hearth right at the transition between brick and fiberboard insulation. (To get an idea of heat saturation of the bricks.)
3. In the arched roof at the transition between insulation and brick.
4. On the sidewall about halfway up, within a couple of inches of the transition to the door/entry. (To measure the degree to which the entry and chimney mass acts as a heat sink and pulls energy from the oven.

[couchpotatoe]

Re: Barrel Vault in So. Cal.

Thanks for your reply, WJW. Your build is coming along nicely. I guess it just a matter of gently drilling with a masonry bit a small hole to the depth desired. I've started beveling my firebricks and am amazed at how easy they are to cut. I've been soaking them overnight and have a large box behind the saw to catch the damp dust. Very little dry dust though. Actually the box is in front of the saw and I work from the back, pulling the bricks through. Its a cheapo HF table saw that I got free with my cement mixer on Craig's list.

I'm still wondering about switching to the multiple thermocouples with a rotary double pole switch. Anyone else out there that has some experience? From my Google research, it looks like it should work, and if all the connections come to one box, a thermocouple in that box would provide the ambient temp reading.

Russ