Documentation, design, software: http://tclcode.com/opentherm/
More technical details: http://home.xmsnet.nl/openthermprotocol/
Homeseer script: Opentherm gateway and script integration into Homeseer by blb
Known supported central heating units: Remeha Avanta, Intergas combi compact cw4/cw5, Intergas prestige cw6
- Forward OpenTherm messages between the thermostat and the boiler
- Report about the messages on the serial interface
- Change the thermostat setpoint
- Set the clock of the thermostat
- Send the outside temperature to the thermostat
- Control the domestic hot water option of the boiler
- Obtain additional information from the boiler
The gateway has been primarily designed for a Remeha Avanta heater with a Honeywell Chronotherm Modulation thermostat. With a lot of help it's now also perfectly communicating with Intergas heaters.
Intergas seems to have issues with encoding the messages in Manchester code when the flame is on or the pump is running. For the gateway to still decode messages and send messages during this time, it has to be less accurate then the Openthem Specification describes. There is a custom gateway firmware available for this.
My gateway has been running stable now for a week so it's time to round things up and mount it on the wall.
Red = Opentherm Error
Yellow = Flame ON
Green / Green = Opentherm Messages