Need help: Ozturk roaster burner issues

[roastero]

I have a new Ozturk OKS 1.5 roaster that has burner issues.The roaster is now prepared for NG, but it's easy to switch to LPG.
Using NG with a regulator, the gas pressure is 25 mbar.
The pilot flame starts quickly, but requires 1 minute in order to remain stable, and to allow me to try to start the burners. Normally,should be ~10 seconds.
Sometimes the burner is starting, but after 5-10 seconds the flame dies.
It's not clear why, It doesn't seem to be influenced by the airflow and gas settings.
Generally, the burners are not starting.
Seems that the gas valve (Nova 820 made by the Italian company SID Group) is not opening the gas to the burners.
The producer support is terrible/missing even thou the product is new and in warranty and I hope that someone has some idea about what could be causing this issue.

 

[MillCityRoasters]

[FONT=&quot]The Nova 820 is listed with a flame sensing device called a "thermopile" that creates a small electrical charge when it's hot. Your 2nd stage solenoid may not be opening because the thermopile is not working or is not hot enough. It has to be positioned directly in the flame of the pilot to work.[/FONT]

[FONT=&quot]I could be completely wrong, but I've seen guys convert their roasters from propane to natural gas (or vice versa) and neglect to convert the pilot. This nearly always changes the shape of the flame in ways that cause problems with the flame sensor.[/FONT]

 

[roastero]

Thank you, Steve. I think that you are right, could be the 2nd stage solenoid that is not opening.

The pilot flame has an injector that is labeled NG, I think that should be OK.
On the next image you can see this injector and how the pilot flame looks on NG.
It seems that the 25 mbar on NG is not enough for this roaster.



Switching the nozzles to LPG and also the pilot flame injector to LPG, the flame is to big and orange.
In this case, the pilot flame remains stable after a longer time, more than 2 minutes. With NG I need less, around 1 minute.
I can reduce the flame size - on the NOVA 820 there is a screw that allows me to adjust the gas flow for the pilot flame.
I also can adjust the pressure on LPG using the regulator. I understood that for my roaster the right pressure should be ~35-40 mbar on LPG.



As I mentioned, a few times I was able to start the burners on LPG but also on NG, but after a while (~5-10 seconds) the flame dies.
Then I need to wait a lot of minutes (maybe 20) in order to be able to burn the burners again. Sometimes it's impossible to start the burners again for a lot of hours.