OpenTherm CH2 (Boiler Channel 2) implementation

[pebl-hank]

Hi there,

https://tasmota.github.io/docs/OpenTherm shows how to enable the OpenTherm implementation in general. However, my heating installation at home doesn't allow to set the boiler temperature via ot_tboiler, but it uses the 2nd channel. I desperately need the second channel to work; even if the OpenThermLibrary does not support it, yet.

In \lib\lib_div\OpenTherm\src\OpenTherm.h you can see that the data model of the OpenTherm protocol already supports all that is needed:
Channel 1 (already implemented):

• set: TSet = 1, // f8.8 Control Setpoint i.e.CH water temperature Setpoint(°C)
• get: Tboiler = 25, // f8.8 Boiler flow water temperature(°C)

Channel 2 (to implement):

• set: TsetCH2 = 8, // f8.8 Control Setpoint for 2e CH circuit(°C)
• get: TflowCH2 = 31, // f8.8 Flow water temperature CH2 circuit(°C)

So as basically a non-programmer, I set up the build chain and worked my way through the code clumsily replicating the first channel code to the 2nd channel. The code is really bad! But it works though on a real hardware! Now I can set "ot_tboilertwo 75" and the 2nd channel boiler heats up.

I now want to address the following, hoping for generous help:

• I made a really bad change in \tasmota\include\tasmota_types.h to be able to store the channel 2 temperature. I rudely just replaced hdmi_addr[2] because it looks like you are not supposed to add things here.
• The changed code needs to be reviewed and optimized.

Here are the couple files I changed. I included the original files to compare them to:
Tasmota-changes-for-opentherm.zip

Is there someone willing to review this and work on it to have it eventually checked in?

I am totally aware that this usually needs to be done via git etc. But I don't feel the code is ready for the common repo and I don't want to make myself ridiculous by adding a pull request. Hope for your understanding!