East London pizza oven and grill

[SableSprings]

Nice video Neil! What you are seeing is a perfectly normal startup. The flue needs to have the "contained air" heated in order for it to rise and start pulling in a good draw. Old timers with wood fired stoves would often light a pine-cone or roll of newspaper and hold it at the base of the chimney to get the flow going. If it's cold outside and you have a tall flue/chimney, the cold air contained in the stack actually resists the warmer air below...just like a plug in the system. That's why if you have a taller chimney it takes a little longer to get the draw started and why the pine-cone/newspaper is almost essential to get things moving more quickly. As the flue heats up, the draw increases and the smoke is pretty much "immediately" pulled up & out.

Hope that explains it well enough. By the way, I have always loved how you can see the layering of air moving in low (cool & clear) and exiting high (warm/hot & initially smoky).

[Gulf]

That’s pretty much what it looks like in cold oven, even with a flue.

[JRPizza]

I think that is fairly normal. One of my friends that had the first oven I ever saw used to say you could burn tires in the oven and as long as your food was below the smoke line you wouldn't taste it. Not something I am going to try
He even had two tuscan style grills, one with long enough legs so his meat could cook up in the smoke area for flavor (hopefully no tires)

[Neil.B]

Nice video Neil! What you are seeing is a perfectly normal startup. The flue needs to have the "contained air" heated in order for it to rise and start pulling in a good draw. Old timers with wood fired stoves would often light a pine-cone or roll of newspaper and hold it at the base of the chimney to get the flow going. If it's cold outside and you have a tall flue/chimney, the cold air contained in the stack actually resists the warmer air below...just like a plug in the system. That's why if you have a taller chimney it takes a little longer to get the draw started and why the pine-cone/newspaper is almost essential to get things moving more quickly. As the flue heats up, the draw increases and the smoke is pretty much "immediately" pulled up & out.

Hope that explains it well enough. By the way, I have always loved how you can see the layering of air moving in low (cool & clear) and exiting high (warm/hot & initially smoky).

Thanks for the explanation. I didn't realise a cold chimney had an effect on the dome, i thought it meant smoke would have trouble going up and would exit out the arch.

I know it's only a small fire but considering I only had a makeshift chimney that faces the roof of the pergola, i was happy with the amount of smoke that went up. Only the odd wispers of smoke came out the arch, obviously the bigger the fire the more smoke, but i won't be doing any bigger until i add the flue.

I agree about the smoke layer exiting. You can see in my video the way it curves upwards without being anywhere near the inner arch.

[Neil.B]

I think that is fairly normal. One of my friends that had the first oven I ever saw used to say you could burn tires in the oven and as long as your food was below the smoke line you wouldn't taste it. Not something I am going to try
He even had two tuscan style grills, one with long enough legs so his meat could cook up in the smoke area for flavor (hopefully no tires)

I thought smoke clears after a short while

[UtahBeehiver]

As Mike mentioned, I start my moderate size stack right under the chimney vent doing a top down burn, when the chimney warms up and is drafting good I push the stack into the dome and cranker up! PS this is after the oven us cured.

[Gulf]

Visible smoke won't disappear until both the oven and the wood inside are hot. An oven where the dome has cleared will still create smoke when a large cold log or excess wood has been placed inside. Even sesoned wood has a certain amount of water moisture in it. That moisture turning to steam cools the oven somewhat for few seconds to minutes. For smoke to "disappear" all the moisture in the wood needs to be released. Then the other gasses in the wood that cause smoke be burned off. For that to happen they have to get up to certain temperature. That temp is created inside the area between the top of the inner arch and the apex of the dome. That is the area where a "reburn" effect is created.

When you get the flue installed you will see some improvement of the draw helping to pull the smoke out, up and away. But still, the visible smoke will striate at a certain level on startup inside a cold oven.

[Neil.B]

Thanks both

[MarkJerling]

Great writeup Neil! And a very, very tidy dome interior!

[Neil.B]

Thanks Mark.
I wasn't to happy when building and thought the uneven bricks were a mess. But the more I look at it the happier I am.

[Baza]

Neil.B - you SHOULD be happy - looks great.
And thanks for asking about the smoke (and putting a video up! Again - I think more of that on this forum for Newbies like me would be terrific!) - as a result, I learned a great deal from the Gentry of the Forum here on how air moves relative to the chimney. I had no idea about starting a fire under the chimney first to "get it going" then carry on with the rest of the firing.

Keep the great questions going Neil!
Looking terrific
Barry

[Neil.B]

After a couple of weeks not doing anything on the oven I decided to make a start on the roof today.
I final figured out something that should work. I basically used a fireproof board with timber running along the top to line up with the groves of the fiberglass pergola roof. Then covered in roofing felt to help protect it from water and mounted it under the roof.
I then cut a section of the roof big enough for the double walled flue connector to fit through and allow water flow. The end of the fibre board flows in to the gutter.

[Neil.B]

Great mental day today. After weeks of not doing anything I finally completed the top of the chimney and joined to the flue. Looks a bit messy shape but the joist was in the way so I had to compromise.
The transition of the flue through the roof is working well, we have had loads of rain recently and everything is dry.
I lent on the outer arch and cracked it, so took it down, I'll worry about it another day.
Because of the shape of the chimney I can fit a rotisserie between inner and outer arch, just need to work out the correct height.

[Neil.B]

Wow, I can't believe my last post was so many months ago. There has been some progress with the build but due to depression not very much.
I wasn't happy with the chimney design and the risk of fire, so i took it down, I'm much happier now.
The chimney/flue design works really well, even at a cold start-up.
I haven't completely finished the insulation and containing insulated blocks, but getting there. The insulation on top of the ceramics blanket was made of 3:1 vermiculite and cement and will be topped off with thermolite blocks.
The thermolite blocks for under the brick floor works very well. 24h after the flames went out I couldn't put my hand on the floor more than a few seconds. Considering I don't have a door and just leant a bit of fire proof board, I was very happy.

Once I finish the brickwork it will be rendered

[Neil.B]