DIY Doctor

Thermostat - which one?

Postby carlosg » Sat Sep 15, 2007 11:49 pm

I have an old Valliant Combi VCW Sine 18 T3 boiler and would like to change the old mechanical room thermostat. The manual states the stat model as a vrt378.
I would love to upgrade to a modern digital stat if possible.
I have checked the wiring of the old stat and there are 3 wires - yellow, red & blue. There is no earth wire that i can see so am really stuck as to what is a direct replacement. anyone any ideas?
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Simply Build It

Postby htg engineer » Sun Sep 16, 2007 10:27 am

The earth wire will be connected to the back plate / fixing plate of the thermostat. Remove the 3 wires and thermostat and the earth wire will be visible.

Wireless room thermostats are quite good, the receiver needs to be wired into the boiler, but the actual room thermostat can be put anywhere in the house.
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