Room thermostat wiring

[Rad1o]

I want to put an extra room thermostat and a 2-port-valve in to "zone" a room that we do not use all that much and instead of turning the TRV up and down I want this a bit more "automatically" controlled.

I have looked at a couple of thermostats and the relevant instructions - a Siemens RDH10 and a Siemens RDJ10.

The terminal has connections Lx, L1 and L2 where
Lx goes to common,
L1 to live feed of the controlled item (2-port-valve) and
L2 goes to changeover contact.

If I only want to switch the 2-port-valve to open or close when the CH is on anyway and I do not want to control the boiler do I just connect Lx to the live feed from the boiler and L1 to the live feed of the 2-port-valve?

Would a 2-core wire be enough? This is what the Siemens instructions show? The valve will be on a 5-core heating wire.

 

[mikely]

An alternative may be to fit a programmable TRV, such as the Honeywell HR20:
http://www.conrad-uk.com/ce/en/product/615952/
I use these in a couple of rooms that we do not need to heat in the morning.

 

[Rad1o]

I looked at them. I am not sure about the looks...