36' low dome neapolitan style

[MarkJerling]

One thing: Over my furnace insulation I added conventional fibreglass insulation, a thick layer. And, over that foil. (No-one here uses foil under the plaster, apparently it slows the drying time of the wet oven construction.) The advantage of lots of insulation is that my oven holds it's heat very well and the outside plaster render remains cold. I have one small area that feels slightly warm, so I suspect I must have a tiny gap there in the insulation, but the rest of it stays cold outside even though it can be 600degC + inside.

[MarvinG]

I suspect it is because my door seals quite well and my door is quite thick, so it effectively blocks the chimney throat too. While some heat must be lost with convection, I do not see this as a major problem. A flue baffle won't hurt, of course, but it's one more moving part so more to go wrong in my view.

True, great Idea!!!
I will make the door quite thick then too!
You know, since I go directly in the chimney of the house, which ends at a hight of about 5 meters there is constant draw. But like this it's basically solved. And yes, I of course am not keen on making a flue baffle. Believe me, connecting my home-made double walled insulation pipe was painful enough. this will not be touched again! ;-)
But it was worth it - it cost me in total about 50$

[MarkJerling]

...

One question has come up though.
When I will switch off the oven and close it over night to keep the heat: Will I not loose quite a bit of heat through the squirrel tail, because I have a constant small drew through the chimney? Would it not make sense to close the pipe as well somehow? Otherwise the oven receives constant cold air to the highest part, right?

That's looking good. I've not noticed that the top of my oven (where the squirrel tail is) loses more heat than the sides. I suspect it is because my door seals quite well and my door is quite thick, so it effectively blocks the chimney throat too. While some heat must be lost with convection, I do not see this as a major problem. A flue baffle won't hurt, of course, but it's one more moving part so more to go wrong in my view.

[MarvinG]

Good Evening


It's been quite a while. The gas is installed by the governmental gas company, the pipes checked that they are all sealed well. The burner works well, as well as the security measures. Means when the flame is too small that it goes off it instantly starts to ignite again. If it starts to rumble because there is too little gas or it creates a constant backfiring it creates an error, and the burner closes the valve. Independently I will have an additional "gas fitter" look over the whole set up. If you wanna see more pictures of the burner or infos I'm happy to share.

I have burnt the oven for about an hour during the past few days. Therefore I built a provisional heat shield since the flame is not in the middle. Today I started to add the insulation.
I have researched quite a bit when to cure the oven. Old method, new method. Did not really understand what is better. But I learnt that I should take it easy to heat it up properly. I'm waiting for my infrared thermometer - before I have this, I will not go crazy withe the temps. So far I could still put my hand in it (top of the oven inside). Was pretty humid every time - you could basically see how the oven was sweating.
Since I have a bit insulation material left I will put a 3rd layer on the upper part of the oven.

After all the insulation is there I will put around a chicken wire to give it some additional stability.

One question has come up though.
When I will switch off the oven and close it over night to keep the heat: Will I not loose quite a bit of heat through the squirrel tail, because I have a constant small drew through the chimney? Would it not make sense to close the pipe as well somehow? Otherwise the oven receives constant cold air to the highest part, right?

below some pictures of the latest progress:

cheers, and happy new president guys! ;-)

[MarkJerling]

Sounds like you have the correct burner. A burner that matches an enclosed chamber of a given volume is different to one used in an application open to the atmosphere. The large oven opening makes it more subject to the flame being blown out.
In Australia a qualified gasfitter is required to do installations. It is not only the burner, but all gas connections, regulator suitability and where and how the lines and bottle location are located that are additional safety issues.

Same here. Recently, a whole house was flattened and several other homes in a neighbourhood damaged badly due to a LPG gas explosion after a gasfitter left a gas fireplace in an unsafe condition and the house steadily filled with gas. You really don't want to play with gas unless you know what you're doing.

[david s]

Sounds like you have the correct burner. A burner that matches an enclosed chamber of a given volume is different to one used in an application open to the atmosphere. The large oven opening makes it more subject to the flame being blown out.
In Australia a qualified gasfitter is required to do installations. It is not only the burner, but all gas connections, regulator suitability and where and how the lines and bottle location are located that are additional safety issues.

[MarvinG]

It's a burner made for pizza ovens with the right capacity of kwh, stepless adjustable with the security measures needed.
What criteria do you mean, when you say it must be suitable?

The Profession "Gas fitter" is not really know here, what is its main purpose. Make installations, or calculate thermodynamics? Of course there are people working for the governmental gas companies. One had a look at it and created a "passport" of the oven. Others created the project for the room (so it has enough frehs/exhaust etc.) and only "open" the gas line - if they approve everything.

[david s]

You must still getadvice from a professional gasfitter. How do you know if the burner you have bought is suitable?

[MarvinG]

thanks for these details!

Yes - I bought a burner from a company which produces such burners. Of course no DIY stuff.
Soon I will hopefully be able to test it!

[david s]

Thanks for pointing this out.

Yes, I have heard of this ban. Before I started my oven I of course searched around gas oven builts and unfortunately did not find a lot.
Thanks for pointing out the security risk. I am of course aware of this. The burner has the solenoid valve. Where is your information from regarding the failure of these valves? or is it the flame detector which would not do it's job?
I also believe the wood thing (I mean I love a real fire, no question) but is mainly responsible for the emotional, nostalgic part. I am 100% sure, that no one could tell a difference in a blind test. Especially since there are no unburnt particles anymore - and i mean, the pizza does not hang in the vent, its on the floor, where mainly the fresh air comes in. For the work on a daily basis however it's a big difference.

Sorry to hear that experience in Sicily. I have never been to sicily, but yeah - foodwise it's a real paradise.

My experience with gas burners comes from years of firing gas kilns. The flame failure devices work not on an electrical solenoid, but on a mechanical system which involves the heating of a tube that sends pressure to open a valve.If the flame on the burner dies the pressure drops and the valve closes the gas delivery. Over the years I've had two of these devices fail. Don't muck around with fitting your own system, get a professional to do the job.
Or better still, skip the gas and master wood firing.

[MarvinG]

Thanks for pointing this out.

Yes, I have heard of this ban. Before I started my oven I of course searched around gas oven builts and unfortunately did not find a lot.
Thanks for pointing out the security risk. I am of course aware of this. The burner has the solenoid valve. Where is your information from regarding the failure of these valves? or is it the flame detector which would not do it's job?
I also believe the wood thing (I mean I love a real fire, no question) but is mainly responsible for the emotional, nostalgic part. I am 100% sure, that no one could tell a difference in a blind test. Especially since there are no unburnt particles anymore - and i mean, the pizza does not hang in the vent, its on the floor, where mainly the fresh air comes in. For the work on a daily basis however it's a big difference.

Sorry to hear that experience in Sicily. I have never been to sicily, but yeah - foodwise it's a real paradise.

[david s]

Be careful, gas plus wood can be a dangerous combination. Imagine the scenario of hot wood coals in a hot oven and the gas flame dies. The hot chamber is then filled with unignited gas that is heated. It is then highly dangerous if it’s ignited. You must have a flame failure device as well as a pilot flame on the gas burner. They are also notorious for failing. There used to be a ban on gas burner discussion on this forum (not sure of the current policy) because of the potential dangers. Make sure a qualified gas fitter installs a suited burner and all gas connections.

Once you are up to pizza temperature there’s no unburnt smoke so there’s no smoke flavour it’s only the pretty appearance of the wood flame that supplies ambience.

I once had an argument with a waiter in Taormina, Sicily about this. The restaurant had a big sign out the front "Woodfired Pizza". When the pizza was cooking I decided to time how long it cooked (it was 2 mins). I walked up towards the oven and thought there was something odd. On peeking into the oven there was no wood or flame flicker, just a big electric element. When the pizzas arrived I complained to the waiter "Forno legne, no legne" (wood oven, no wood). He replied that it was "Bad for the pizza". My Italian is pretty poor so I didn't argue. Probably all the wood in Taormina was already gone, supplies too expensive and the restaurant too lazy. They also tried to overcharge us, we had a party of but ordered 5 pizzas. They tried to charge us for 6. It was the only time in Sicily that we had pizza. So much other good food to experience there.

[MarvinG]

Yes, it will be mostly gas, and some wood for the taste. Depending on how well the burner works with its security mechanisms.

[david s]

Ok, so will it be gas rather than wood fired?

[MarvinG]

It is recommended that no more than 45 degree bend should be used as the draw becomes severely compromised. A horizontal flue pipe is likely to create smoke issues, which in your case, being indoors could become a big problem. once your flue is heated the draw won't be an issue, but at light up it's likely to be a problem. Some folk install an electric fan in the flue to overcome this problem.

Hi david s

Yes, I see what you mean. To attach the oven into the wall pipe (which is horizontal unfortunately) I will have a pretty big 45° +45° angle.
However what you do not see, is that after the 1.5 meters horizontal, there is another 3 meters vertical through the chimney (not perfectly sealed attached) but it should help create some draw as well.
In the end that is the max I can do with the given situation. I keep you posted how well it goes. I hope to be able to adjust the flame with the gas nicely to start slow. In the mornings of the next day, the oven should still be warm, so I usually do not start from zero...
Thanks!