Drayton Digistat+

[HPLow]

I bought a Digistat+ room thermostat to replace my current stat which I believe has stuck as the heating would not go off at preset temperatures and need help/advice from you pros on how to wire up the new Digistat+.
My current stat has 3 wires red, black and green. Using a test pen I turned the heating on and checked.

Red = Live
Black = Live but light on test pen gradually goes dimmer as i reduce the temp on the stat
Green= presume it is earth.

The new Digistat has
1=Heating satisfied (off)
2=Call for heat (on)
3=Common/switched live from time control.

The last time I tried to change the stat I blew the programmer and had to replace it- I am not going to make the same mistake again and need your help guys.

Cheers guys

 

[Gasguru]

Don't assume the green is earth...is is often borrowed for a switched live. What is the exisiting stat?...does it not have a diagram in the cover showing the connections ie live from programer, switched live (call), neutral (not always used) and earth.

 

[HPLow]

The old stat is just a cheapo and ther are no wiring diagrams. I have opened up the old stat again, turned the heating on and the red is live alright and the black only becomes live when the temp dial is turned down, calling for heat i presume. Can I just use the red and black in this instance, red for Common and black for call for heat, ignoring the rest?? Will be be a safe bet??

 

[twgas]

can you find where the other end of the cable goes as

the black only becomes live when the temp dial is turned down

doesnt sound right

 

[HPLow]

Mick
I prolly did not make myself clear. On opening up my existing stat and checking with a test pen and turning the heating on, the red wire from the programmer to the stat is LIVE. The black wire becomes live when I turn the temp dial down. I am assuming the black wire goes back to the boiler calling for heat as the temp is below the set temp. Hope it makes sense. Anyway can I just use the red and black for Common and Call for heat??

 

[twgas]

still cant understand turning it down for on

can/did you find where the other end goes and what the black and red are connected to.

 

[HPLow]

Oh dear, what I really meant is when I turn the temp up to call for heat the black becomes live- I will check where the 2 wires lead to.