Propan-Gas Wall-Oven controller (DO NOT TRY THIS!)

[M*I*B]

Hello there...

...at the moment I'm thinking about such a control ... well ... not quite right ... The controls are safe, but I originally had a Raspberry Zero in mind.
The question that I am just asking is, is not that possible with a 07S ?!

The basis is a so-called outdoor wall oven. This is a stove, which is screwed to the wall and conveys its exhaust gases directly through the wall to the outside. These stoves are usually operated with city gas (30mBar), but can also be converted to propane (50mBar), so you can use normal camping gas. Exactly such a stove I have installed for a year in my garage (see attachement).

In the meantime, I have already given the oven 5 120mm fans to bring the warm air faster in the garage. This has significantly improved efficiency, significantly reducing gas consumption; the noise level disturbs an apartment, but not in the garage.
A main problem remains: These boxes can not be remotely controlled and adapted to climatic and other conditions. So rebuild ... (and yes: I am well versed in gas plants).

With a RaspBerry this should not be a problem. It has more than enough ports to serve all sensors and actuators.
But what about a 07S? The ports are far from enough. I would have to work here with expanders (I²C?). And that's exactly what I need your help with ...

Here is a table of the IO's:

Inputs:

1) Room temp (1wire)
2) Burning chamber temp (ADC, CrNi element or near like that / too hot)
3) NOx/Gas sensor (LOW- active if Alarm)
4) Infrared flame detector (redundant!)

Outputs:

1) Gas-Valve Master (direct mounted at Propan-Bottle)
2) Gas-Valve Stage 1 (in combination with Stage 2 ...)
3) Gas-Valve Stage 2 (... generates Stage 3)
4) High voltage ignition
5) PWM for Fans
6) Emergency - ShutDown


With my FHEM the ESP should then chat via MQTT. On the one hand, I would like to record the status and, on the other hand, be able to set the target temperature depending on the weather and the time of day.

Furthermore, there are of course compelling relationships, which are mainly due to safety and safe operation. There is e.g. the external NOx / gas sensor. If an alarm is triggered, all valves must be closed immediately and the system shut down completely (discharge power supply). Even if the IR sensors are out of flame even though at least one valve is open and the ignition has been completed, all valves must be closed and a fault reported, which can only be cleared manually on site. These are the two main dependencies ...

Ok ... So it's easy to ask: Does anyone want to do some brain storming with me and develop solutions to do it with a 07S?

[TD-er]

The most important part should be that whatever fault state will occur, some mechanical switch should turn back to safety automatically.
Also there should be no electronic/software only way to detect the fault situation.
For example high CO-values, high temperatures, etc.

ESPeasy is a great tool, but I dare not to guarantee stability on which someone should risk its life.

[M*I*B]

Yes you are right. There are a few more things that need to be done about safety. But they come in the course of development even more. Quite good would be a watchdog / heartbeat, which immediately generates a ShutDown.
Perhaps one should not leave the detection of a flame to the ESP, but generate self-sufficient and classical analogue (or both in parallel). In addition, one could also use the thermoelectric (existing) sensors in parallel to the IR sensors. Then you would have in contrast to the current configuration not one, but even three safety circuits ...

But that's exactly why I decided to share this project with you here. There are probably many good ideas out, which can be used elsewhere ...