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Strooom / SmartTherm

Controlling a Junkers heating (Eurostar ZWE24) with an IoT thermostat
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Is this also compatible with 1-2-4-6 Junkers heaters? #11

Open ltctceplrm opened 5 months ago

ltctceplrm commented 5 months ago

Like the TOP 30/375-2 ZBS

Strooom commented 5 months ago

Mmmm, I don't know this heater.. as it's 4 wires, it looks like it's using a different protocol or interface. We need to know more info about what is on these 1-2-4-6 wires.

ltctceplrm commented 5 months ago

1 is for power 2 is a CAN Bus High 4 is ground 6 is CAN Bus Low The thermostat is a TA270 with this wiring QPWlgL7 RUmD7FR And this is what the wiring in the heater looks like: M3vKHou

nagyrobi commented 5 months ago

CAN Bus is a completely different type of animal...

Strooom commented 5 months ago

Indeed, my design is intended for the older 'analog' thermostat interface. I have never used an ESP32 with CAN, but it seems the MCU has this interface. So you could modify the design (hardware ánd software) to make it work for a heater with CAN. Biggest challenge will be to find out what messages/protocol to talk to the heater.

nagyrobi commented 5 months ago

Interesting that Junkers/Bosch used EMS protocol (proprietary interface) so far, since when they switched to CAN?

nagyrobi commented 5 months ago

But, given the fact that the heater has the connector labelled as 1-2-4-6, there are chances that you can use the analog solution provided by this hardware on the 1-2-4 pins only. You have to check in the service/installer manual of your heater, if the communication protocol of the heater can be switched from CAN 1-2-4-6 to 0-24V 1-2-4. In my case (a Junkers Ceraclass) it was possible to choose between EMS and 0-24V 1-2-4. Of course the original thermostat won't work in this case.

ltctceplrm commented 5 months ago

So you could modify the design (hardware ánd software) to make it work for a heater with CAN. Biggest challenge will be to find out what messages/protocol to talk to the heater.

I think that would be well above my skill level unfortunately, especially because I don't know how long my heater will still last. Next one I'll definitely find one that is compatible with every smart system possible 😉

Interesting that Junkers/Bosch used EMS protocol (proprietary interface) so far, since when they switched to CAN?

My heater (Junkers TOP 30/375-2 ZBS) uses Heatronic 2 and I think EMS is Heatronic 3-4 right? I think my model might be too old then perhaps.

But, given the fact that the heater has the connector labelled as 1-2-4-6, there are chances that you can use the analog solution provided by this hardware on the 1-2-4 pins only. You have to check in the service/installer manual of your heater, if the communication protocol of the heater can be switched from CAN 1-2-4-6 to 0-24V 1-2-4. In my case (a Junkers Ceraclass) it was possible to choose between EMS and 0-24V 1-2-4. Of course the original thermostat won't work in this case.

That would be very interesting but will it still support modulation?

nagyrobi commented 5 months ago

The modulation is done by this circuit!

ltctceplrm commented 5 months ago

I looked at the manual for the heater and not the thermostat and they do mention that there are two ways of connecting a thermostat, one of them is for the TR-100 with the 1-2-4 cables and the other is with for the TA-270 with the cables like I have. Here's an image from the manual image

If I understand correctly I could just unplug the cables going to the green section on the right and instead connect the smarttherm board to the white section on the left, with cables 1-2-4: image

Strooom commented 5 months ago

Yes, the manual also mentions the TR21 and this was the thermostat that I reverse engineered and for which the hardware is providing compatible signals.