Vaillant 624 system boiler with Unistor and 2 zones CH/UFH - CH zone help needed

[Baz1312]

Could be a faulty VR10 but I would edge toward incorrect configuration of the parameters. As 831bunny said, I stand corrected, the vr10 connects directly to pcb in boiler. Check that connection first. If ok may be worth doing a factory reset and starting over with the setup. Best bet is to phone group service and book a visit if your still having problems after that. Hope this helps. (System diagram 3 variant B appears to match your description of the system.)

 

[acideraser]

Thank you Baz, I will check connection to the PCB and as you suggested possible next step factory re-set and setting it up again.

 

[The831Bunny]

Sounds like the VR10 may be connected to the wrong 'pair' at the boiler. The DHW sensor connection should be to the pair terminating in the SMALL plug with Orange and Black wires (cut off plug and use a connector block). Not the large plug with Brown & Black wires. The large plug is C1-C2 as shown above in the drawing. These are NOT used, and would fire the boiler when linked in DHW mode.

 

[acideraser]

Sounds like the VR10 may be connected to the wrong 'pair' at the boiler. The DHW sensor connection should be to the pair terminating in the SMALL plug with Orange and Black wires (cut off plug and use a connector block). Not the large plug with Brown & Black wires. The large plug is C1-C2 as shown above in the drawing. These are NOT used, and would fire the boiler when linked in DHW mode.

It's thin grey wire coming from the top left corner, connected to the brown terminal in the top left on the board which is next to blue white and pink terminals...

 

[The831Bunny]

That's the connection block for the outside temperature sensor. Only the outside sensor for the weather compensation is connected here. The VR10 should be connected to the Orange/Black flying lead found at the left hand side of the boiler, not within the PCB housing.

 

[The831Bunny]

This is what you are looking for.

 

[acideraser]

Thank you very much The 831 Bunny!

 

[Baz1312]

The 831 bunny is the man !
Give me a VCW any day !!!
Best boiler ever built

 

[acideraser]

Sorry silly question, vr10 has brown and white wires, connection plug orange and black, so which one connects to which one?

 

[Baz1312]

Not a silly question. I don't think it will matter, the pcb is measuring the resistance across the VR10 to give a temp. reading. Take your pick.

 

[acideraser]

Thanks Baz, will try that

 

[acideraser]

Thank you very much guys, I connected VR10 to correct pair and system works the way it should now, problem solved!

 

[The831Bunny]

Thank you very much guys, I connected VR10 to correct pair and system works the way it should now, problem solved!

Glad you got it sorted!