Vaillant VR 33 connecting on older boilers

[EPK]

I have seen few interesting topics related to Vaillant VR 33 module, and I am writing with the hope that somebody can help me.

I have an older Vaillant AquaPlus (VUI 280-7) boiler in my house, running perfectly, and I have purchased the Honeywell Evohome system, working with my boiler in ON/OFF mode currently.

I would like to add the R8810 module to Evohome for controlling my boiler through the OpenTherm interface, but unfortunately my boiler does not have an OpenTherm interface.

I learned that by adding VR 33 module to a Vaillant boiler this could be achived, however VR 33 should be connected to the main board via X31 connector, which does not exist on the main PCB board of the boiler.

I also found out that another Vaillant module, called VR 39 can add an eBUS interface to my boiler via X6 connector, which I have, but I still do not know how to connect VR 33 to VR 39, by which OpenTherm would be available, because VR 39 does not have the X31 connector either.

I would be very thankful if somebody could help me in this regards. Any advice and solution is welcome.

Many thanks in advance.