OTGW with Techneco Toros Vision TVPT 2 & EVAs

[beertje]

(apologies in advance for the stupid question) but I would like to install the opentherm gateway kit (from nodo-shop) for my Techneco Toros Vision TVPT 2 pump/boiler system, but I am not sure where to connect it to...

According to the manual (https://mediacdn.remeha.nl/-/media/webs ... 26T124915Z) X7 is for OpenTherm connections

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When opening up the system, it looks like a module/connector that is plugged in (presumably going to the terminal blocks (EVAs):

pcb

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terminal block

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Looking at the two EVAs I can see that it also has OpenTherm connectors and EVA1 has the Honeywell Chronotherm Touch connected to it:

eva1

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And EVA2 has two empty OT connectors:

eva2

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Do I connect the OTGW to where the Honeywell Chronotherm Touch is connected and in turn connect the thermostat to the OTGW (like a daisy-chain approach so to speak), or can I connect the OTGW to EVA2 (the one that has a free OpenTherm connector)?

I am not interested in messing with the options or sending commands/instructions from the OTGW, purely I am interested in stats/data of how the system is running etc. - kind of read-only mode.

Thanks in advance.

[hvxl]

I have no experience with equipment with multiple Opentherm connections. It is unclear to me if they control different aspects of the boiler or not. If the connections are equivalent, what happens when the attached devices issue conflicting instructions? Unfortunately, the manual does not provide any information on this.

Then there's the situation that you have 2 EVAs, each with 2 OT connections. The boiler only has 2 OT connections. So it is unclear if the panels are wired in parallel, or if each of the OT connections is only connected to one of the two panels. If they are connected in parallel and you hook up the gateway to something that already has a thermostat connected on the other panel, both devices will stop working.

So, my guess for the best chance of success would be to connect the OTGW where the Honeywell Chronotherm Touch is currently connected, and then connect the Touch to the OTGW. The Touch may obtain some information that you otherwise wouldn't know to request. But of course you can also try to connect the boiler connector of the gateway to an unused OT connection and see what happens. It should not be possible to damage anything by doing that.

For a less hit and miss approach, you can measure the voltages on each of the OT connectors of the EVAs. Steady 0 volt means that the connection is probably not wired up to the OT connection of the boiler. Below 8V, with periodic spikes up to 18V, indicates that some OT device is connected. A stable voltage of 20 to 24V suggests an idle OT connection. You can try to connect your OTGW there.