Wrong dimensions - Help!!

[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.

[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.

[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.

[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.

[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.

[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

[stonylake]

Re: Wrong dimensions - Help!!

I have also been following this thread, and i have to agree with splatgirl... i did pizza's last nite, and used about a half dozen pieces of cherry, about the size of your forearm.. started with a handful of scrap oak 1x1's that i get from the local molding manufacturer. when i got home from work tonite, the oven was still at 165 degrees and that is without a door (which my welder should have finished very soon)... ambient temps were in the high teens overnight, hit high 20's during the day. you aren't going to be happy with it until its built according to the plans..

[Ken524]

Re: Wrong dimensions - Help!!

I have a rocket scientist (really) friend... I couldn't convince him for anything that a brick oven and wood fire would reach 1000 degrees.

He must have forgotten that hi-temp smelting has been going on since 4000BC - no rocket science needed!

[splatgirl]

Re: Wrong dimensions - Help!!

I made exactly that point. Along with raku pottery.
As I said, sometimes even smart people just don't wanna use their thinker.

[lwood]

Re: Wrong dimensions - Help!!

Can the rocket scientist read a thermometer? It a well known fact that the temperature of a wood flame is in excess of 1,200F. So what's so hard about that. BTW, we made rocket motor nozzles as early as 1958. In 1983, we were weaving graphite fiber into a 3-d matrix for use in icbm rocket motor throats and nozzles. There is nothing new about that technology now. I did the the final inspection of the first graphite fiber mono-cockpit, for the McLaren Formula 1 racing team that is now used as the standard every racing team on the circuit. Have him tell you something new about composite structures and I'll tell you how we did it in 1985. Yes, even smart people just don't wanna use their thinker. haha

[peterthewolf]

Re: Wrong dimensions - Help!!

Hey lwood and all-
I really appreciate the input.
Ok, here's the thing. We have been good honorable citizens with someone who for 10 years has delivered pretty consistently. By good citizens, I mean we felt comfortable dribbling the money out all through the job until it went on just too long. So we've paid out a lot for what is now sitting there. If a fix *can* be done, and he won't or can't accomplish it, we'll have someone else do it.

*But* - starting over? Budget got spent already for the project. So let's keep at the creative grindstone here. We've already sent the mason a letter establishing our boundaries and next steps (including spending it elsewhere if he doesn't fix it, all the way to functional, according to our direction). So we are free to try with or without his help at this point. Only because there's a good history will we let him try it- but from here out it is completely on our terms.

So:
Order of fixes:
--Step one, drill hole and experiment. if drilling a hole at 63% height fixes it, great.
--Step two, plug it up and put a ceramic kiln shelf about 8 inches down from dome peak, so the 15 inch high door goes 63%. Remember, door is 15 high, but flue is 18 high, an is located inside the door, not outside it. So smoke draws up at 18 even if the door is closed. But we can block that flue completely simply by taking off the vent cap above and turning it flat side down on the pipe. So do we need to match the 18 inch high flue down to 15 inches door height?? If so, perhaps just an inserted metal ring the diameter of the flue can be inserted into it, and jut down to the top of door level, or a piece of metal can be made to make a fake "sill" containing flue opening up the pipe. Then experiment.

Last step, if the floor is still not heating and holding temp - would by deduction have to be it's insulation saturation.

So- Wet insulation is insulation cold and drawing heat. But would some thin sheet metal on the existing floor, covered with a new layer of brick, substitute in dry heat mass to fix this, or would all that heat just conduct right down through it, through the metal and original floor? Waste of work and material?

If it would not fix the floor, could we chisel up the existing floor (within the internal diameter of the dome), then dig out the vermiculite below it, and put something down there below the vermiculite to keep it from sitting directly on the slab? Or-use some other kind of material to insulate that is not so it is not water attracting like vermiculite is?? Anyone know why we've seen guys on utube breaking up glass into the under-floors of their hornos in Mexico when they build them? (Man if that works, I now recall we have a 30 gallon can full of broken glass that got forgotten behind the barn when we moved our recycling storage. Is it possible that there is another material than vermiculite that might work in a wet environment? As it is, the way this slab was built, there were two inches of reinforced concrete put down onto ground level *before* the vermiculite was put on top, so the vermiculite now sits two inches *above* the ground level that is wet. That slab was poured into a wood mold, and then the vermiculite went on top of that in the mold. Although vermiculite can absorb water, is it possible that it, once dry, won't pull up that much moisture ( I mean really water) vertically like a sponge or siphone from the flat top of a 2 inch raised slab of cement on which it sits?

If that is possible, then of course the dome walls are still sitting on the original vermiculite, if it is down to ground level on cement. But heat is higher on walls, and reflects downward from a (functional) ceiling, and we don't cook right against the walls. So do we need to care about what's going on beneath the rim of the dome base, really?

On a parallel thought, I teach wilderness skills and so of course have a couple of primitive shelters on our land here. One of them is my private meditation hut and consulting place for students. I built it kind of hybrid: since it's location is toward the bottom slope of our acre the ground can be quite wet and muddy in winter. So I went modern hybrid a little. Instead of willow saplings, I used large redwood branches from our giant trees nearby as uprights for the dome (to take many more years to rot). I raised a rim of cement up about 10 inches above ground level around the diameter of the floor and upright branches to shed outside water from the roof in the rain, outward. Then onto what would now have been the dirt floor (with the rim, now appearing to be a "sunken" floor - water saturated - I put
a few inches of nice pea gravel to raise the floor above the surrounding ground level where the water travels. Through wet winters, I have a nice dry floor. I'm sure plenty is wet below, and if I were to hermetically seal the structure, the under floor would vapor up and make the place a mold pit. But with existing air flow that never happens in several years. Can a parallel to this be done below the oven if we have to go as far as dealing with the floor- just perhaps using something beside vermiculite as the insulating medium...or to set new vermiculite just on top of something...say like over an inch of gravel sitting on top of the existing base slab before replacing the brick? And even adding even one additional layer of inch thick brick over it for just a slightly raised new floor if at all?

Folks this has gone on a long time but it will be really good that we are completely informed. Whatever we do, we want to do this in the next couple of weeks and get it 'off the desk'...and onto the plate

So tally ho everyone, let's try some last rounds here please
Thanks for your consultations; we're very grateful!

[brickie in oz]

Re: Wrong dimensions - Help!!

? Anyone know why we've seen guys on utube breaking up glass into the under-floors of their hornos in Mexico when they build them?

Because they get confused, glass is an excellent insulator for electrical current, but not as a thermal insulator.

They see insulator and its all confirmed for them and its game over....

[david s]

Re: Wrong dimensions - Help!!

It is the air trapped between the pieces of broken glass that creates the insulation. In Turkey they also insulate under their oven floors with broken glass and presumably have been doing so for eons.

[dmun]

Re: Wrong dimensions - Help!!

Lets run this by one more time.

Gravel is not insulation.
Sand is not insulation.
Broken glass is not insulation.

Maybe if I say it one more time it will break through to the front page of google.

As to the bigger issue, here's what I think. You've built a little artificial cave in the hillside. Caves are by definition cold and damp. I've spent some time thinking about how you could isolate the inside of this structure from the cold and damp, and I've not come up with anything.

[Wiley]

Re: Wrong dimensions - Help!!

I've followed this thread for sometime and have written responses three times and deleted before sending, three times. Bummer to tell someone that they are just throwing good after bad and that regardless of what they do at this point they still have the proverbial "sow's ear".

But you seem determined to forge on, so in hopes of adding something constructive that I don't recall anyone suggesting: You might consider digging a curtain drain around the outside. I'm suggesting a righteous curtain drain, in fact two. One a few feet further out from the other. This should stop the lateral flow of water to the WFO from the hillside.

Now on the downside: you will be doing alot of work to install the drains. You will also make a mess of the landscaping around the WFO. All in hopes of making somewhat usable what in all honest evaluation is a pretty, yet poorly designed WFO. It won't cure the poor proportions nor wrongly positioned door, but it will probably allow the base to dry out. For the amount of effort (to say nothing of money) you could IMHO more easily tear down what is there and build something that works and that will do what it is expected to do.

As for amount of time, money and energy already spent and that you will be walking away from...ever know anyone who got divorced? This is small potatoes.

Bests,

Wiley