Home Automation Domotica Forum Europe, Bwired Forum

Problem I have, log attached:

• Nest V3 thermostat hooked up to my boiler with my new OTGW from Nodoshop in between
• Nest has H73 error, meaning that there is no Opentherm communication
• Logging only shows "T00030000 Read-Data Slave configuration (MsgID=3): 00000000 0", repeating every second.
• Somehow I did manage to send an override (CS command) to the boiler and the boiler turned on and heated the water to 50 degrees (tried multiple times, in retrospect I think only one time it worked)
• Troubleshooting done: measuring connectivity of wires to thermostat, reconnecting the thermostat showing ('thermostat connected').

Unfortunately the log you collected was with the OTGW in monitor mode, rather than the normal gateway mode. In any case, there is no evidence at all of communication from the boiler.

You say you successfully set an override setpoint to the boiler. At what time stamp in the log was that? Normally an override setpoint is done with a TT or TC command, which actually changes the setpoint on the thermostat (if supported), not the boiler. To my knowledge, the Nest doesn't have support for a setpoint override via the opentherm interface.

Anyway, the first problem to investigate is the boiler interface. See the troubleshooting section on the web site for instructions on how to do that.

Today I tried again to install the gateway, now it works!

My (likely wrong) conclusion at the time was that the link between thermostat and gateway didn't work, since I was able to turn on the boiler with a CS command.

My final hypothesis indeed is that the communication between boiler and gateway was flaky, and perhaps one time the CS command came through, but I indeed did not see much more communication between boiler and gateway. The evening I had the issue, I removed the gateway and the thermostat and boiler restored their connection. Next day I tried connecting the gateway again, and it magically worked!

Cheers!