36" Build in Texas

[david s]

When the soot burns off the top of the chamber the fire will want to gallop away as it burns more efficiently. There will be a persistent ring of black on the lower half of the oven. Beware because this is the stage where damage is likely to occur. This is because the crown of the oven is getting really hot with the moisture having been removed there first, whilst the lower part of the dome , still black because of the moisture presence, is way cooler. This huge difference in temperature, of course means a huge difference in thermal expansion which creates stress that can result in cracking. An infrared thermometer would tell you this, but it’s not necessary, just take it slow when you see this condition.

[JRPizza]

When I transitioned from a very rectangular opening to a mostly square chimney, I had to do the scallop that Russell talks about above. My adapter plate was not flat on the bottom but had a circular projection downward that I had to accommodate so the adapter would sit flush

[mongota]

McGooster

Here are a few pics of my oven throat, I posted this for someone else so it might help you as well. 10" square to 8" square to 8" round pipe. You can scale it to your desired size. It was a simple idea and easy to build:

https://community.fornobravo.com/for...961#post431961

Best, Mongo

[McGooster]

Thanks everyone for the tips on curing. I’m just going to take it very slow and pray everything goes well.

I have a few photos on progress I made today. Finished outside arch and almost closed the dome. A little perplexed on if I should just cut three equal pieces and close it or add a small layer and then close it with one piece plug. Hole is about 5” diameter on top and ~4” diameter on the inside

[MarkJerling]

It really does not matter how you shape your plug. Either three pieces or another layer and one piece will work equally well.

[McGooster]

Update. Finished the dome and the flume area. Going to start the insulation today and potentially light the first curing fire today. Hoping to get the stucco going later this week.

I feel like the Durvavent chimney pipe I got is a bit too long (36”). I may return this and get a 24”

[UtahBeehiver]

I would NOT stucco until the oven is fully curred. Water when it turns to steam increases by 1500 times so it is possible to build enough pressure under stucco to crack it. David S suggest placing a piece of plastic over the dome while curing and if see condensation then the oven is still wet. Are you putting in a dome vent at the apex?

[McGooster]

Good to know. Thank you. I will definitely wait until I finish curing to start the stucco. I am also planing on using some sort of plastic so that I can see condensation.

Can you explain more about the dome vent? I am not planning on doing that as I am unaware. Thanks UtahBeehiver

[UtahBeehiver]

You can do a forum search and you will see dozens of different types but the purpose is if the insulation get wet then when it sublimates to steam the vapor has a way to vent. Gulf and I use a auto case breather vent that you can get at any auto parts store for less than 10 bucks. it mounts into a 1/2" pvc bushing set in the stucco. Gulf reinforces his bushing with a little wire mesh around the bushing it in the stucco.

[McGooster]

Ahhh ok that makes sense. And something I had not thought of. I will look into just purchasing an auto hydraulic breather vent like you have shown above. Great point.

This forum has been so helpful. So many things I haven't thought of, that you folks have pointed out, and have been a game changer. Thank you

[MarkJerling]

Update. Finished the dome and the flume area. Going to start the insulation today and potentially light the first curing fire today. Hoping to get the stucco going later this week.

I feel like the Durvavent chimney pipe I got is a bit too long (36”). I may return this and get a 24”

Taller flues tend to draw better. I'd leave it at that height if I was you.

[david s]

Don’t be in too much of a rush. If you have used the homebrew as your brick mortar, as it contains Portland cement (calcium silicate based), it’s strength will be considerably enhanced if kept moist for at least a week. Following that about a week of drying before any drying fires as steam spalling is a common problem should any moisture suddenly turn to steam. If you used refractory mortar (calcium aluminate based) it achieves full strength in 24 hrs but still allow some time for it to dry naturally before any fires, for the previous reason.

[McGooster]

Thanks everyone for the feedback and advice. Update - Had my third curing fire. Got to around 400 - 450 degrees for around 3.5 hours. Everything seems to be going ok. I have these white spots in the oven and I am not sure if that is cracking or just mortar that isn’t coated in black soot. Not sure. No major cracks that I can see. Hoping to do 3-4 more curing fires before feel comfortable getting to temp and trying pizza.

Also found out that my tarp has multiple holes in it and now a lot of my insulation is wet. Hoping the sunshine will help dry it out.

[Gulf]

I doubt that it is cracking. Though, that will occur eventually. IMO, the oven is still wet. There may be a little void in the mortar behind those white spots. Or that may be just some fine ash that settled in a projection in the brick joint. Anyways, 450 degrees is about 500 short of where you will start see a true dome clearing. Every square inch of your oven will be sooted up before you will see it actually start to clear. Take your time. Don't rush it.

[david s]

If you see any steam, back off, you're going at it too hard. Best to forget pizza for now, but you've probably stored enough heat to roast a chicken or two, or do some baking with the heat you've generated.