Programmable room thermostat

18 Mar 2007
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United Kingdom
I have an Ideal Mexico boiler, a Landis & Gyr RWB2 programmer and a Honeywell V4043H 2 port valve.
It looks like the hot water is heated by gravity and the CH by pump.

Is it possible to fit a Sunvic TLX 6501 programmable room thermostat to this system and if so can this be done by connecting the wires from the thermostat by breaking into the dark grey wire into the V4034H.

Any help will be appreciated

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Assuming there is no room 'stat at the moment, yes it's possible but it's the brown wire you need to "break into" as you put it.

thanks for your post,

my V4043 has an orange wire connected to the pump, a blue which is neutral, a dark grey which comes from terminal 4 (CH) on the programmer and a light grey which comes from terminal 3 (HW) on the programmer.

If I use the orange wire this would presumably cut off the supply to the pump but leave the valve open, if I use the dark grey will this close the valve and turn off the pump.

Is the dark grey the brown ?

Switching off the pump will turn of the heating but I presume the boiler ill still fire, is there a way of turning off the boiler using the room thermostat ?


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