Nest Learning Thermostat no existing room stat

[DaveG54]

I'm installing the Nest Learning Thermostat to cover heating and water in a single Y based system. There is no room stat the existing system relying on thermostatic radiator valves only. The existing wiring centre (where everything comes together) has the connection for the room stat jumped between call and com so the heating is always on.

How do I wire the Nest using the wifi stand?

How do I generate the call for heat?

Thanks

[zoeuvre]

Hi DaveG54, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Are you located in North America or Europe? What is the make and model of your HVAC system? And could you send us a photo of your previous thermostat wiring configuration and a photo of how you connected the wires to the Nest Thermostat base? You may also use our Compatibility Checker to determine if a Nest Thermostat is compatible with your heating and cooling system. 
 

Keep us posted.

Best,

Zoe