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Hi All, can anybody advise what is the correct set-up for SYSTEM Vaillant boilers?
I’ve just completed this install . Run a new 2 core cable from boiler to nest heatlink. Install vr33 believe it connects into x32 port . Connect the new wire to vr33 and nest heatlink, remove old thermostat. Setup nest as open therm
This is an excellent question. How do you get Nest and VR33 to work together on a SYSTEM boiler, WITHOUT a VR65/VR66. Everyone else on this thread seems to describe how they use both VR33 and VR65 /VR66 Control Centre.
Here is my experience having done exactly as SamThor describes (and also bridged the RT24 and disconnected the RT240 live):
The CH is working with fine with modulation, but the boiler is not firing when there is DHW demand from the thermostat, neither is it applying the DHW temperature when both are running. My CW and DHW valves are still being controlled by the Nest thermostat and the DHW boost/charge signal is being sent via OpenTherm (D025 shows “Ext eBus signal: Cylinder charging: On” when there is hot water demand via Nest and off when there is no demand). However, the boiler refuses to fire up, presumably because it is not connected to VR65/VR66 to know the actual status of the valve/cylinder thermostat?
Has anyone managed to install VR33 and an Opentherm thermostat on a system boiler without a Vaillant Control Center? Thanks