Baxi system boiler and Opentherm Discussion Thread
Hello
Does anyone know if its possible to connect an Opentherm thermostat such as a Nest to a Baxi 800 System boiler.
I know its possible with a Baxi 800 Combi but I cannot find any information on achieving this with a system boiler.
I wondered if its possible to control the radiator flow temperature with say a Nest connected to the opentherm inputs.
(also controlling S plan CH & HW zone valves with its 240V outputs.)
Then for higher flow temperatures needed to heat the HW cylinder reliably to 60C, I would like to slightly modify the standard S plan to hot water priority with one relay (disabling CH zone valve when HW zone valve open) and add the Relay PCB kit from an Baxi IFOS System kit (without the weather comp sensor).
Its my understanding that 240V on the Relay PCB kit when installed temporarily overrides any current boiler flow temperature to 80C
Thus when the HW cylinder made a call for heat, the Zone valve to the HW cylinder would open and using a simple extra relay the central heating zone valve would close. (if it was open - the modified S plan). At the same time the HW cylinder call for heat would also cause the IFOS Relay PCB to boost boiler flow temperature to 80C.
Then when the HW call for heat ceased flow temperatures would be controlled by Openthem control and CH flow would be resumed.
Does anyone know if this would work
Many thanks
Ian
Baxi system boiler and Opentherm for the original thread on Plumbers Forums
Hello
Does anyone know if its possible to connect an Opentherm thermostat such as a Nest to a Baxi 800 System boiler.
I know its possible with a Baxi 800 Combi but I cannot find any information on achieving this with a system boiler.
I wondered if its possible to control the radiator flow temperature with say a Nest connected to the opentherm inputs.
(also controlling S plan CH & HW zone valves with its 240V outputs.)
Then for higher flow temperatures needed to heat the HW cylinder reliably to 60C, I would like to slightly modify the standard S plan to hot water priority with one relay (disabling CH zone valve when HW zone valve open) and add the Relay PCB kit from an Baxi IFOS System kit (without the weather comp sensor).
Its my understanding that 240V on the Relay PCB kit when installed temporarily overrides any current boiler flow temperature to 80C
Thus when the HW cylinder made a call for heat, the Zone valve to the HW cylinder would open and using a simple extra relay the central heating zone valve would close. (if it was open - the modified S plan). At the same time the HW cylinder call for heat would also cause the IFOS Relay PCB to boost boiler flow temperature to 80C.
Then when the HW call for heat ceased flow temperatures would be controlled by Openthem control and CH flow would be resumed.
Does anyone know if this would work
Many thanks
Ian
Baxi system boiler and Opentherm for the original thread on Plumbers Forums
