Would really appreciate some help, I have just got a nest and need some help on installation and type of flex I need, I did try to install it but think I might of gone wrong some where, i have a Worcester GreenstarHE combi boiler with simple wiring, I've supplied some photos, I have a thermostat control on the hallway wall
It seems you only have Ls (Line supply) and Lr (Line return) going to thermostat, there is not wire to Ns (Neutral supply) so either Nest needs to be close to boiler (Not too close or you can get RF interference) or it will need an independent supply.
Nest needs two supplies anyway one to base and one to thermostat the latter either from base or a USB outlet.
As far as I am aware although the boiler has option for eBUS control and Nest is OpenTherm enabled the eBUS in the Bosch only works with their own thermostat, think called Wave? So it has to be on/off control.
However Wave (It that's the right name?) will only control one room, it does not have the follow commands that Nest uses. So it does not link to TRV heads (Energenie) in the way Nest does.
How you wire really depends on how easy to get a neutral wire to where your going to fit Nest. I have heard Worcester Bosch has an EMC problem, but not had it myself, so I think I would try fitting the main Nest unit near the boiler first and see if it works.
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