I had a Buderus GB142 boiler installed in 2008. DHW and 3 zone hot water heat. Saturday morning (two days ago) thermostats on 70, house at 63 and scrolling through the Service button shows code OH (standby/no call for heat). The circulator pump was running, all three zones are calling for heat yet the boiler does not receive/answer the call. DHW is fine, no issues.
The Chimney Sweep button will fire the boiler and run for 30 minutes, as expected per the service manual. Once the 30 minute cycle completes the zones continue to call for heat but the boiler does not fire and the control panel displays OH/no call for heat (Heating System Status LED off, Burner Operation LED off)
This AM the house was at 60 and stats at 70. Same story as above re: pump running, OH code, etc. Switched one stat to off, the other two as low as they would go (they are heat only, no on/off). Waited 30 minutes and moved the stats back on/to 70 and unit now fires and operates as it should, with both Heating System Status and Burner Operation LEDs lit. All zones receiving 151 degree heating water (current outside temp @35F)
My installer/service guy had to leave the business due to health issues and I've had difficulty finding a qualified tech (Monroe, CT and interested in recommendations). I'd like to get some feedback here to help me understand what may be going on with the unit so I can have a productive and intelligent conversation with service techs I call.
Thanks in advance!