Wrong dimensions - Help!!

[splatgirl]

Re: Wrong dimensions - Help!!

Yikes. I've been following your thread since the beginning. The only thing that isn't a huge bummer about this is the exterior stone work. Gorgeous. The rest just makes me sad. I'll never understand why people can't be bothered to read the instructions. Even smart people!
I have a rocket scientist (really) friend who's entire career was spent designing equipment to measure the temperature of rocket exhaust. I couldn't convince him for anything that a brick oven and wood fire would reach 1000 degrees. He had any number of reasons why my information had to be incorrect. He thought I was crazy and making stuff up!

For the record, I bet I've barely used half a cord of wood in two full summers of near weekly firings, including what it took to cure/dry my fresh build.
I'm with lwood. Between the water absorption issues and the crazy dimensions and flue thing, I'd start over

[Neil2]

Re: Wrong dimensions - Help!!

"If this will actually cure the problem, I'd let him drill that hole and try it. "

Put the top of the hole at the 63% height.

[lwood]

Re: Wrong dimensions - Help!!

Peter,
You have some basic design problems and I think you should consider rebuilding with a untainted mason. With the hearth sitting on the ground and water gushing out of the hillside, I think you should consider it before you burn down any more forests. The oven is absorbing moisture from the ground and as soon as you drive the water out with firing all the energy is going into driving the water out. As soon as you stop firing the water rushes back in. Check the vermiculite, I'll bet dmun is right the vermiculite soaked.

The oven needs to be isolated from it's surroundings and needs to dried out completely in-order to work properly. If you are never getting over 180F you haven't even reached the boiling-point of water. I would recommend that you excavate underneath the hearth and build a free-standing structure to support the hearth slab and then build the oven from there. You need to be sure the water is getting no where near the oven. The French drain can be behind the structure to divert the water but there should be an open cavity underneath the hearth. I'm sure you could do it directly on the ground but it must be well insulated and sealed from moisture. That seems more difficult than building the block structure. Maybe there is a way to do this without a complete tear-down but I sure don't see it.

From your discussion with your mason, it's clear he built something different than you wanted and didn't follow the plans. He built you a horno and he did you a dis-service. He may be a friend, but he knows nothing about building a pizza oven. He has done enough damage so far. I wouldn't let him touch it again. You may be able to save the fire brick in the tear down and the blanket but not much else. Sorry to be the one tell you this.

[dmun]

Re: Wrong dimensions - Help!!

The south american "horno" with the vent in the dome is notable mostly for it's inefficiency. I don't know how cutting a hole to let heat out is going to solve your efficiency problems.

If you want to bust a hole in something, break out the side of the enclosure and see if, as i suspect, the vermiculite concrete is sopping wet.

[Laurentius]

Re: Wrong dimensions - Help!!

Hi Peter,

I fired(1000 degrees in 90 minutes) my 42' Pompeii up Saturday and cooked pizzas and two loads of bread, Sunday(485 degree when opened) I roasted a chicken, this morning I had to open the door for 40 minute so the temp would drop to 230 to cook pulled pork (8 hr slow cooked) when I finished the temp was still around 200, so I loaded it with wood to dry.

[brickie in oz]

Re: Wrong dimensions - Help!!

A hole in the top of your oven will just let the heat out, heat like smoke finds the quickest way out.

[peterthewolf]

Re: Wrong dimensions - Help!!

Had a surprise visit from the stonemason this morning; woke us up. Hey great to get things 'off the desk' in a conversation. That was fun... He'll be on hold until we have a working oven.

Here's how it went. Half a cord of split oak through 5 days firing hot (three of them straight through and overnight) and we have no significant changes in temps, plus it's still only 150's to 190's on the floor next morning. After seeing no real cracks on day 3, I went for it and stayed big and constant on the fire.

He looked in the oven and said it was "raw" (uncured). But that only the inside door arch containing the 8" flue looked like it got enough heat to cure by visible brick color. It is clear from what he said that although he had referred to the FB plans, what he built is a Mexican horno. That's different. For them, he said, there needs to be a hole just off center through the top of the dome, one to two inches max diameter for smoke to escape through the top of the dome itself. They call that a 'flue'. Why? Because, he said, when there is a smoke layer down to the top of the door, the fire isn't getting enough air to burn hot, and the smoke blocks heat from the dome...so the dome can't heat up and then heat the floor. Putting a one to two inch hole max through the top of the dome just off center he said, will eliminate the smoke layer and it will fire hot.

If this will actually cure the problem, I'd let him drill that hole and try it. If it doesn't work, we could just ram a brick plug back up inside the dome, pour cement, vermiculite, and then cap it with a rock and we're back. Any experiences or insights about this?

We looked at another Italian pizza oven tonight at their party, firing pizzas. Not a Forno Bravo, but Italian. His walls were a foot vertical, and the dome was so low it was barely arched up at all. Door is lower and wider than ours. He only burns about 8 sticks the size of my wrist to forearm, and it only takes 2.5 hours to heat to 500 where he cooks pizzas in 5 minutes. That's more feedback on lowering my dome.

Further comments? Little drill hole a waste of time? I'd appreciate it!

[peterthewolf]

Re: Wrong dimensions - Help!!

If you have lots of vermiculite, the blanket is not necessary. Nice but not required.

Dmun- this part's ok. All that firing and it was only slightly warm outside again this morning. So that part's covered; thanks.

[dmun]

Re: Wrong dimensions - Help!!

One more thing. (I) missed until now the business of an *additional* insulating blanket beneath stucco for igloo types. We didn't do stucco, and didn't use an additional blanket before applying the surface rock.

If you have lots of vermiculite, the blanket is not necessary. Nice but not required.

[sonomacast]

Re: Wrong dimensions - Help!!

I only scanned your thread quickly but why not raise the floor in order to lower the dome and door, cheap. quick and easy

[peterthewolf]

Re: Wrong dimensions - Help!!

Oh, great. Y'all - I so appreciate your help here. This is no fun in that we've had a wonderful relationship with the artist for 11 years. He really ran with this one and essentially told us that he would do the plans, and was very experienced with WFO's. W had not reason to think otherwise. But whether this is a cultural or language communication difference to say yes when it was no or he didn't know, when I was asking questions, or he just got strong headed like "I'm the expert here", we don't know. We are beginning to wonder... if after all this time is it possible, that he was not able to read, or to comprehend the pictures, but said that he understood them all along... We just don't know. That's all water under the oven (hopefully not); we need to fix it.

As we all get further folks, with the new input on possible heat sinking, I'm concerned to get a fix and not think of demo-ing. After all the beautifully successful (bid) projects this guy has done for us, this one was first ever as time and materials. This job, beside now having problems in discovery, hemorhaged time and cost - ridiculously past the original estimate. If I told you how much by the time he finished it you'd think I was nuts. There's a final balance left at least to pay to him, thank God. We are ethical people and for a *properly working* oven we will gladly give him the rest. If not it's not working, once we know the real problem(s); he is welcome first within that budget to correct it, or we'll have to give it to someone else who can.

I *do* hope heat sink is fixable somehow, because yes, that's what the base was - on the ground. It was two inches reinforced concrete sitting directly on the sandy clay - a soft sandstone that we are on here, (rock hard dry in summer, digable and saturated in winter). Then covered with 4 inches vermiculite, then mortar about 1/2 inch thick into which the bricks were set. No airspace under the slab. If this is a heat sink, there you go. At least due to water absorption, would it help to put a metal liner, say thin steel or other metal plate pieces, on the existing floor and then layer some sand and brick up one more floor layer on top of it? That could stop direct "sponging", at least through the floor itself, but not cold from below. Where the walls sit on the slab there seems nothing we can do. Of course, at 40 inches floor now, we'd the have a 36 inch floor due to the rise up into a narrowing dome. That's less fun. Unless we used half-thick firebricks and set them flat side up. We'd about keep the 40 then.

One more thing. (I) missed until now the business of an *additional* insulating blanket beneath stucco for igloo types. We didn't do stucco, and didn't use an additional blanket before applying the surface rock. But again, very little heat seems to be coming through the dome exterior even on day two of all day firing. It feels not very warm to the touch out there on top of the dome.

On the design: That was our design, but we did of course assume low dome which we didn't get. It's our local stone in this county (CA wine country, Sonoma Co.). He came up with the cement grout seams on the dome, and the beautiful angled edge all around the front. I wanted a warming fireplace that would throw heat high *and* low by having a low-set fireplace. We'll eventually suspend a high clear acrylic rain cover up over that section of the patio, say 11 feet up for weather so we can be out there even in drizzle or light rain - way more charming with a fire than with a standing propane heater. We put the tools into long bamboo handles (about 10 feet long) that are reasonably balanced and easy to handle so that even with a fire outside, we can reach into the oven with them and still be far enough back not to get it's smoke in eyes. Tough we discovered to navigate with an enthusiastic crowd making pizzas, we found out on inauguration night, but it added to the fun!

Jay- He's from Michoacan, been up here much of his life, has built many hornos in Mexico and here he said. But as we understand, from clay not brick. This was his first of brick, though he said he could follow the plans. We didn't have any red flags first because he does beautiful brick work. Something just went nuts on this job and we are shocked on all levels. Anyhow y'all, in the spirit of getting solutions, can we keep going on this?

As of now, I've fired two evenings, then smoldered down overnight to next morning, out about lunchtime. Then two more days, where I lit up in the mid morning and burned all day, stoked at night and let it go until next morning, then once outside next morning lit it back up all day. That's 2 eve's, and 2 whole days plus their overnights. And another tonight for good measure. Temps each morning are only 150 to 200 on the floor, and 250ish walls straight back by IR gun before firing back up. Dome this morning about 300. Between the first original firing, and these days, I've burned so far about 4/10ths of a cord of split dry oak. This is another rea$on I want to be aggressive about fixing it.

So we've got these possibilities as we are exploring:

1. Stick a kiln shelf up into the peak to lower dome 8 inches, to get it *closer* down at least to the floor and more toward parabolic (or at least more heat reflecting) than distantly pointy. Flat, but something to make flame circle over and send heat down instead of going nearly straight up and ending up there.

2. Put a metal moisture liner(?) that won't self destruct on the existing floor cover, then little layer of sand, then brick one layer over it (that lowers the dome effectively too by 2.5 inches brick thickness) ???
3. The above steps or any combination would increase door height to 63% from existing 50%.

Talk to me. What else? Thank you all so much. Oh I can hardly wait for the phone call I'll be making shortly to this guy...especially because I don't have anything definitive yet. I'd love to know what I'm going to require for a fix on this puppy.

Yes, we built it into the hill. We dug back, leveled, left space at the corners about one foot, and where the dome bulges out to meet flat hill angles, only a few inches. We stuccoed the hill cuts onto wire mesh and left no exposed dirt first. We mortared that ground around with a slight flow out toward each front side of the whole structure to channel water. Look for a little black circle at your kneecap height on the right side of the picture. That's a short piece of black 3 inch flex drain through the half wall, so rain water can exit forward and away. Yes, this hillside holds and dispenses a tremendous amount of water in Winter. The cement bulge of ground that you can see at the base of the whole structure in front is a 1 foot wide open swale that runs all around the base of the hill to carry water away in the rains. The fireplace floor is bridged over it. From both seepage and real flow from gopher sized holes punched in the stucco retaining wall all along the hill into the swale, much water can flow out from that hill. What on earth (pun) can we do - short of demo-ing and lifting up a *new* oven to counter absorption and heat sinking??

Brickie- Yes, two flues. They aren't required as it is a BBQ by definition. We did it for extra safety, appearance, and overkill in case requirements ever tighten up in the future.

Finally, I'm keeping about 3 pieces of split oak (as I can through the day) burning all the time when I'm around and awake...how much longer should we keep this up until we can all say it is "cured" and "dry"?

Thanks all; please write back soon! And Brickie, thanks again for posting the photos.
Peter

[lwood]

Re: Wrong dimensions - Help!!

Yes if the hearth slab is in contact with the earth, the earth is acting like a big heat sink. Is that what they call global warming. LOL Also possibly absorbing moisture.

[texassourdough]

Re: Wrong dimensions - Help!!

I am no WFO expert but that is one of the more unusual ovens I have seen - no idea what nationality/heritage it represents. Any idea where your mason is from? (Curious, nothing else!)

I am with dmun. IF you can get and keep it dry you should be able to make it work. But... built into the hillside is definitely a potential problem. Mine was done that way...except we excavated into the hill and built a retaining wall around the base to be, and then built the oven freestanding.

Keep firing!
Jay

[dmun]

Re: Wrong dimensions - Help!!

Unlike some of the posters, I'm not too concerned about your tall dome. We've seen those and they seem to work OK.



I am, however, concerned that it seems to be built into a hillside. I'm worried that there isn't proper isolation from ground water, and your structure may be a sponge soaking up water constantly.

Once it's dry, your oven should heat up and clear in a couple of hours, using a wheelbarrow or two of firewood. I'm thinking that oven has never been dry.

[lwood]

Re: Wrong dimensions - Help!!

The second flue appears to be to vent the outer arch. That shouldn't be necessary. The door looks awfully big for a 40" oven. I don't think your mason read the plans, especially with putting the door outboard of the flue. Once you get all the water out, we can make a better assessment of how to fix it.