I have a new IDEAL Combi boiler with three zones for heat. All 2 wire. (R & W), They are powered by a 24v transformer. No Zone control box, So the circuit is: Transformer -> Thermostat(S) -> Zone Valve(s) - Transformer. The (T,T) connection that activates the boiler is triggered by the "end switch" from either of the 3 zone valves. This is independent of the power for the Transformer/Thermostat/Zone Valve circuit. The Zone valves are the wax expansion type and take a couple minutes to activate. I do not think the boiler is to be activated until a zone is actually open. SO trying to insert the Nest power connector it looks like I would have the R from the transformer go to both of the R wires on the power connector and the R that goes to the Thermostats. (4 wires together). The W coming back through the Nest-Zone Valve(s) would go to white on Nest Power connector (on the Left). The C and W on the Right would go to the W on the transformer. Does this sound correct? Attached is a diagram. I do not know how the Nest Power Connector is spoofing the thermostat to make it happy with 2 wires so I am not sure it will work. Two thermostats in the Heat only Zone are Basic Nest thermostats and have the N260 error. The other is the Nest Learning thermostat and also has a totally separate AC system in it (3 wire R, Fan, Comp) + the R&W from the boiler. This one seems smart enough to be happy with the power it has. One basic Nest has no access to other wiring without Sheetrock and paint matching activities. (external wire is unacceptable) So i would really like the power adapter to work.
