Remote and automatic Masonry heater management

Hi guys,

I'm starting in the Arduino world and firsst project is to help a colleague with his masonry heater : Basically, the idea is that he needs to close the exhaust tunnel once the combustion is done ... meaning something like 1 and a half hour after he ignites the fire. As he does that in the morning, he would like to be able to ignite the fire, leave for work and be able to check on his smartphone the fire status and to command the closure of the door. V2 of the project would be to have the system automatically close the door ... but that will be in a second time.

So here is how I saw the project : - as a center piece, an Arduino Uno - wifi connection through an ESP8266 - a few sensors, such as temperature, maybe CO2 or CO to check the level of the combustion for this part, we are not sure yet what will be the good signals, so, first, we consider just logging quite a lot of data to decide later

For the actuator part, the door being a rather heavy (1.5kg) sliding plate with crude sliders, I go for a NEMA 17 stepper motor and a TB6600 driver. Actual actionning will be done with a rack/pinion system ... and I'm strongly thinking about using lego parts for that

As I don't have much place for end of course sensors, i was thinking of using a ultrasonic sensor (HC-SR04) to ensure proper position of the door in open and closed position.

Currently, I have quite a lot of the eletronic parts (Arduino, sensors, ...) and i'm starting basic stuff to ensure everything work properly ...

For the sensors, easy duty, many great tuto and I managed quickly to obtain the data I want

For the motor, i forgot to buy the proper power supply, so it will be tested later ...

Now, the one part where I'm really struggling is with the Wifi connection :

I start first with ESP01 programmed through the Arduino : I managed to make them work and connect through the TX/RX pin of the arduino and pass some AT commands, but everytime I tried to update to a more final wiring with the TX/RX of the ESP connected to other pins of the Arduino (like 6/7), I never managed to make it work, and now, I don't even manage to access them directly anymore ...

Reading someplace that ESP12e were easier for beginners, I buy some of those, and I managed to do a few things with them, ie connecting my temp sensor directly on it and sending the data on thingspeak ...

Now, what I'm having difficulties grasping is how to use this ESP12e as a Wifi extension of the arduino ... I have the impression the Arduino will be better for managing several sensors and actuators and processing informations, and I would like to only use the ESP as a comm channel for pushing information on thingspeak or some other server ...

Is it possible doing so ? What I was initially trying to replicate from some tutorials with ESP01 was to create AT commands in the Arduino sketch to push the data. Is it the best way to do it with the ESP12e ?

Thank you in advance for any feedback or advice you may have on my approach of this project !

How comprehensive is your public liability insurance?

Agree about the insurance lol.

Such a system would need to be done by an experienced industrial gas engineer - eg it needs hard wire interlocking in a fail safe manner with the combustion control system and needs to be in line with gas engineering codes and practices .

Do something else - as implied if it went wrong you could be liable for damage, loss of life and so on .

Well, thanks for the caution notice, but from my point of view, this project may sounds more safety critical than I believe it is :

The only interaction I have with the heater is through the exhaust binary opening/closing. So should the system malfunctions : it would either not closed the chimney when required (at the end of the combustion), and in this case, the heat would go outside, which would be a waste, but not really critical ...

Or, it could close prematurely the chimney, thus reducing draft and leading to premature extinction of the fire. This is the one case that could be troublesome as it would mean incomplete combustion before the actual extinction ... Fail safe system for that is that the house in question is equipped with legal CO, CO2 and smoke detection sensors ...

So, from my point of view, it seems rather safe to play with this single door which is already part of the heater ...

I come back to my main question about wifi connectivity : could you recommend on how to communicate between an Arduino Uno and a ESP12e ? from my understanding, if I want to use the 12e as a ESP01, I should change its firmware to AT command ...

Alternatively, couldn't I use the NodeMCU firmware for a more elaborate communication between the 2 boards, exploiting more fully the ESP12e ?

Thanks you in advance for your thoughts,