36" Pompeii Dome - Thailand

[danhem]

The oven is getting better with each fire. Dome clearing nicely but still not getting fully clear down the walls and still recording around a 30F heat loss through the hearth on the following morning. Is this typical to lose heat down through the floor or is it that my floor is still wet? Strange that no heat loss is recorded during the fire.

Onto my the next steps now - v-crete the outside with one 1.5" layer before giving the oven (and myself) a rest for some time whilst the v-crete dries. I'll also look at finishing the front area off with a granite/tile surface.

I wonder if I'll ever get bored of watching the fire, something about it - man, fire, food. Great fun .

[danhem]

Continuing to fire the oven and have now started to load it with fuel for higher temps. The upper dome bricks are clearing after an hour or so of intense fire and as others on the forum experienced, a distinctive smell comes off during the clearing. As UtahBeehiver previously suggested, lower wall bricks are not yet clearing so I have to assume that the under floor insulation is still wet.

Recording oven temperatures; after 2 hours of fire in the oven center my dome bricks seem to retain a temp of around 750F. After moving the fire to one side, the floor immediately records around the same 750F but quickly drops to around 500F. Clearly these temps are some way below what I am hoping to achieve.

During the fire the heat loss through the dome, walls and hearth is practically zero. However checking the temps this morning the hearth has spiked 30F as the oven has cooled overnight. Again I have to point to a wet floor insulation here, but find it strange that during the fire (fuel loaded burning for around 5 hours) the hearth heat drain records no spike in temp. The outer parts of the CF board insulation I can see appear to be fully dry. This remains a work in progress but I see each fire exactly as that, a little progress and a step in the right direction.

Good news is we got pizza out of the oven and it tasted as good as any wood fired pizza town . A couple of failed dough attempts over the past week after following recipes online revealed that humidity in the air here calls for much less hydration in the dough, as like-for-like recipes were coming out far too wet. I settled for a hydration of 57% with 00 Flour, and this seems to maintain sufficient water whilst proofing nicely overnight in the fridge. Just like the oven, the cooking side of things remains a work in progress.

[UtahBeehiver]

Wet floor insulation is the hardest to get out. As mentioned before when the dome clears and you see a black ring around the floor courses the oven insulation is still wet. Wet insulation also readily transmits heat so that is why you are seeing temp spike on hearth. You will actually, smell when the dome starts to clear, at least that is what Gulf and I have experienced.

[danhem]

Have reached the dizzy heights of 700F in my curing program, yet to see the carbon clear but hoping this will happen as I raise the temperature. It's definitely a nervous time wondering if something will go wrong but without tempting fate the situation is so far so good.

I recorded some heat under the hearth, which I'm happy about as the under floor insulation got very wet. The heat drain through the weep holes are perhaps telling me that moisture is being driven out. Also recorded a very slight temp rise on the outside of the oven dome and walls. Very small temperatures so not overly worried about that. I'm now considering the v-crete application after the next round of cures.

Managing the fire is a skill for sure, knowing when and where to position fresh wood can either make or break a good fire. I have employed a local wrought iron company to make an andiron to help with the fire management. Lumping a fresh log on top of burning logs has presented mixed fortunes for me - the new log either sets alight of it collapses the fire into a smokey mess. With the andiron I'm expecting new logs to sit with sufficient airflow as to avoid fire dampening and choke smoke.

Up to 700F with my fires and maintained the temp for a good 3-4 hours. Unreal amount of fun. Prepared a lasagne (4 hour ragu, hand rolled pasta, buffalo moz) and finished it off in the oven. A great moment and one of the most satisfying meals I have ever had. I may just attempt a pizza next week after a couple more curing fires, as the oven stands now the temperatures reached are probably a little low to cook pizza.

After letting the embers die down I believe I hit a stage of euphoria. I dont think I've ever seen colours like that.....maybe it was the wine...and beer.

[UtahBeehiver]

At some point you will see the dome clear of carbon and work its way down. If you see a black ring around the bottom it is an indicator that the floor insulation is damp.

[danhem]

Still working through the curing process with small fires, raising the temperature every second day and setting a longer fire maintaining the temperature. Up to 600F now and maintained that for around 3 hours today. I checked the temperatures 3 hours after letting the fire burn out and it seems that the brick temp retention decreased by around 50% from their peak.

At 600F the outside dome (with 3" FB insulation) showed no signs of heat loss and the under hearth temp did not increase either. The under oven floor fibre board exposed at the front of the vent landing is still damp and I have no way of knowing how damp the rest of the FB is.

I'll aim for a short burn at 700F tomorrow followed by a longer 700F the day after. I'm hoping that these longer burns are help to dry out under the oven floor.

I have a hairline crack in the outer arch during the fire but this all but disappears once cooled. Not a nice sight to see at first but I'm putting it down to an expansion crack at this stage.

The fire to reach 600F dome apex temp was pretty impressive to watch. Seems that to get to 800f/900f the fire will have to be a monster.

[danhem]

Caveat Emptor, this is where we see a lot of builders get impatient. They cure their ovens too fast and too hot and crack them. The turtle wins the race in curing. You can start with charcoal briquettes (cook something while you at it) maybe a couple times. This heats the oven to about 200-250 F, then really small fires, one extra piece of wood can really spike the temp on the dome almost immediatedly. If you are seeing steam, you are running too hot too fast. David S suggest placing plastic over the insulated dome and if their is condensation forming then oven still is wet.

I am setting some small fires and have slowly built up to 300F. Even getting to that temperature with charcoal briquettes and some small strips of wood has been a challenge. All my wood is damp so even if I wanted to push it higher I'm not sure I could. Also the underfloor ceramic FB is wet. The weep holes under the hearth have been weeping, it's a real fight to keep the rain out and the oven was left uncovered whilst being hit by an unexpected downpour. i am covering the oven with tarp when the rain comes and uncovering as soon as it passes. If the trap is on for a few hours, a lot of condensation builds up.

Question is - Is it even worth battling again the wet weather right now with daily fires getting the dome apex to 300F? Should I try to push the heat further or set some low fires for a long period?

[danhem]

Insulated and chicken wired - damn horrible job, probably the least enjoyable part of this build. What followed later in the day however was the first curing fire and that made up for the morning shift.

Its humid here with sporadic heavy rains. I've tried my best to cover the oven dry but the under oven ceramic FB has sucked in water. I set a small fire with BBQ briquets. I use these for my home made tandoor oven. I lit a couple of briquets and expected the oven to fire up to 200F quickly. In the tandoor after an hour a pile of these briquets with hit 900F without trouble.

An hour in the pompeii after slowly adding briquets the doe hit 130F. Careful not to push to hard too fast I added more fuel without much gain. I concluded at that point that moisture and humidity must be my enemy so let the fire burn with the occasional addition of fuel. Over 2 hours later the internal temp began to rise rapidly and some areas of the oven hit the 200F mark. I moved the fire to cooler parts and once they hit temperature pulled the blaze and let settle for another day.

Its amazing at even these relatively low temperatures to feel the moisture coming off the bricks.

[UtahBeehiver]

Caveat Emptor, this is where we see a lot of builders get impatient. They cure their ovens too fast and too hot and crack them. The turtle wins the race in curing. You can start with charcoal briquettes (cook something while you at it) maybe a couple times. This heats the oven to about 200-250 F, then really small fires, one extra piece of wood can really spike the temp on the dome almost immediatedly. If you are seeing steam, you are running too hot too fast. David S suggest placing plastic over the insulated dome and if their is condensation forming then oven still is wet.

[danhem]

Finally took delivery of my chimney flue and anchor plate, a custom job and a pretty good effort I think. It was a month in the making so I had plenty of time to cut bricks ready to stick in on arrival.

Knowing that the refractory mortar used for the dome build is likely to fail me a some point, I have been on the look out for home brew ingredients. Thankfully another forum member based here in Thailand has only recently sourced the hard to find hydrated lime and has been kind enough to provide a 25kg bag (big shout out to SvH for this).

I wasn;t overly happy with the look of my outer arch and got sick of hanging around whilst waiting for the flue to arrive, so decided to put the home brew to its test and ripped down the arch (I was pleasantly surprised at how much force was needed to break the arch with the refractory mortar, it leaves me with a little bit of hope that the dome will hold) and rebuilt with home brew. Also filled in the gaps between bricks on the outside of the dome with home brew. Boy do I wish I'd had this stuff from the start of this build.

Built up the vent chamber and installed the anchor plate. I went with UtahBeehiver's anchor plate fixing by sandwiching the plate between bricks.

I let the brew set a couple of days under plastic wrap before sliding the flue over the anchor extension to look upon what has been in the making for some time. I'm pretty happy with the way it has turned out and it feels like a huge milestone complete as I don;t think i'll need to cut any more bricks.

I have purposefully left enough space to allow for the flue to be removed. I'm concerned about high winds and with 5 months of monsoon around the corner I will wrap the oven tight after the curing process to protect from the weather. I will have to look at the best options to secure the flue from the elements going forward but at this stage the removable flue seemed to be the best step.

Plans to insulate and lath this week before starting the curing process and tidying the odd jobs up such as mortar cleaning etc.

With any luck we may get a pizza cooked before the weather comes in or my dome caves in!

[danhem]

Got my vent figured out and bricks cut into place. I am waiting for my chimney to arrive so have not stuck anything in place yet incase I need to make adjustments for the anchor plate.

I had to cut some notched bricks to create a rectangular chamber of sorts as my vent opening was formed by the arch making it difficult to work upwards. The notched bricks make the arch work vertically before the rectangle chamber is closed into a 6inx6in square with some angled cuts. I'm hoping my anchor plate will sit snugly on top. I do have some wriggle room so am confident that I can slot things into place.

I began to grind an angle on the lower outside of the inner arch to encourage smoke flow upwards. I don't have much of an idea on how well my current set up will draw but pleased nonetheless that I'm getting very close to the end of the brick work.

[Yokosuka dweller]

I had similar issue where my vent opening was a bit too tight but on the sides, not front to back. When my anchor plate arrived I scribed the circumference onto the bricks and used angle grinder to get a roundish transition. As you said you're going to have 1,5m chimney, so with that length it should very well.

[danhem]

Looking good danhem. Only point of caution is if, potentially, you might run into some constraints when fitting the anchor plate. I can't see the flue opening dimensions from your photos. Overall 60sqi is good, I think. But given the standard anchor plate is square it might constrain that down a lot because your flue opening is so rectangular. I don't know about semi arch openings, so it may not be an issue at all. Alternatively one option to increase the 'squareness' of the opening could be to very carefully grind off an inch or so at the inner arch overhang.

Yes I will be looking to square the arch off as I go vertical - just trying to work out how the arch can go upwards to form a flue gallery. Seems like JRpizza and RandyJ had a similar issue to over come in their builds.

I realized after completing the vent opening that the depth is right on the button at 6” so a little tight and a definite over sight. I’ve been so careful not to make any stupid errors all the way through the build and leaving the vent right is an error.

I have plenty of width room to allow for a narrowing into a square as I go upwards. It will reduce the area dimensions but again I think I have a lot to play with there for a 6” flue.

I plan to grind an angle on the outside edge of the inner arch to aid with smoke flow into the vent chamber so hope to gain some more depth space during that process.

Eventually I hope to create a square vent chamber for the anchor plate to sit on. Not sure how I’ll do that but running with some ideas on that at the moment based on inspiration from an number of builds.

This seems to be the last real hurdle before insulating the outside and setting the curing process into action.

[Yokosuka dweller]

Looking good danhem. Only point of caution is if, potentially, you might run into some constraints when fitting the anchor plate. I can't see the flue opening dimensions from your photos. Overall 60sqi is good, I think. But given the standard anchor plate is square it might constrain that down a lot because your flue opening is so rectangular. I don't know about semi arch openings, so it may not be an issue at all. Alternatively one option to increase the 'squareness' of the opening could be to very carefully grind off an inch or so at the inner arch overhang. But yeah, check this on other builds in the forum. Some people also speak of a venturi effect, so even if your opening is less than the required area, as long as your chimney maintains the required sq/area you might be fine.

Btw, I'm glad to hear you found a good option with that pizza company, yes, you are probably avoiding some potential trouble and miscommunication pitfalls by not going with the local welder/metal works option.

[danhem]

Outer arch and vent opening done. Can't seem to make this build pretty regardless how much effort I put in but the arch seems locked in solid enough so I'll take some pleasure out of that and move on with a touch more experience under my belt.

Looking at ordering my chimney tomorrow so whilst waiting I've been looking at how to transition from the vent. At the moment the vent opening presents around 60 sq inches.I am thinking of building up on top of both the inner and out arches to try and connect over the vent opening somehow to position the anchor plate on top. Still trying to figure it out but made a start on some cuts today that may be a good starting point.