I tried to install a Nest thermostat to control one zone of a three-zone system heated by a Buderus boiler. When I call for heat the boiler comes on with no problem. When I turn down the heat to ambient temperature the boiler turns off but the relay begins to click and does not stop until I call for heat again. It is a two-wire system and the Nest is a Nest Pro A0013 model.
Thanks for getting back to me. We are in the USA. We replaced the Nest model A0013 with the original Honeywell dial type thermostat since the clicking of the relay was doing nothing positive and the outside temperatures were hovering around -6 C. It is a two wire system with three Honeywell's controlling three zones in the house. All are two wire, red and white. I hooked the red to the "Rh", the white to the "W" . The wires were well seated in the nest connectors, they had been stripped well back (almost 2.5 cm, having been wrapped almost twice around the Honeywell connectors and had no slack when installed in the Nest). Again the relays started clicking at ambient house temp (~20 C) but stopped when I set the temperature to 30 C which of course engaged the boiler. Unfortunately, I have no pictures since it is not my house and the original thermostats are back in place. However, this is the third and only unsuccessful Nest installation I have done with this type of Nest product. The first installation controls two zones of a forced hot air furnace heated house, and the second controls a single zone boiler system all are two-wire systems heating systems. Both have been running well with no issues.
I'm sorry for the late reply, and I know it's been a while, but I wanted to ensure that everything was covered here.
How's it going? Are you still experiencing any HVAC issues? If so, it appears that it's most likely a power-related issue. Please take a look at this article and let us know if you need more help.
Thanks for assisting, Archie.