OpenTherm on older Vaillant boilers

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OpenTherm on older Vaillant boilers

Postby EPK » Tue Jan 23, 2018 9:03 pm

I have a Honeywell Evohome system installed in my house working with my Vaillant Aqua Plus (VUI 280-7) in ON/OFF mode.
I am thinking of adding the R8810 OpenTherm module to Evohome with the goal to further improve the comfort in my house.

The issue I am facing is that my boiler does not currently have an OpenTherm interface.

I discovered that Vaillant has 2 extension modules:
1. VR 39 - that can add an eBUS interface to my boiler, via X6 connector on the main PCB
2. VR 33 - that can convert OpenTherm to eBUS, via X31 connector on the main PCB, however this connector does not exist on my mainborad (neither on VR 39)

Ideally if VR 33 could be connected to VR 39 and VR 39 to the main PCB of the boiler, the problem could be solved.

Does anybody have any experience in this regards? Any (other) solution is welcome.

Note: The boiler is still in a good shape, so no reason to replace it yet with a more modern one that has an OpenTherm interface,
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