Still busy on the opentherm interface with my Nefit HRC24/CW4 and I think it will continue for a while because it is very difficult to do. I am now busy with the Nefit Service key to communicate with the NEFIT Hvac system. The service key has Infrared, bluetooth and RS232 or USB. So lots of possibilities to communicate. I can get a lot of data with this key out of my Nefit HVAC. Now I am busy grabbing the protocol etc.
For now I'm still controlling the Nefit HRC24 with a Xanura SAX15 which I have build in my Hvac (heating) system. If I switch this actor on with my system, the thermostat also says the heating is on, this is because of the opentherm protocol the Hvac is using. Its not optimal because if the thermostat puts the heating on, I'm not able to switch it off with the SAX15. You can connect any relay or in my case the Xanura SAX15 to connector 1 and 2 of the Nefit HRC24 HVAC system. his a is a potential free (potentiaalvrij ?) connector.
They are right below the connectors 2 and 3 where your thermostat goes in.
With this option I'm now also able to control my Nefit heatingsystem with my cellphone (sms and by web)
See also topics:
Online House in the netherlands. Domotica, Home Automation.