Wiring a Thermostat (Drayton)

[dmh1973]

Hi

I currently have a Horstmann central heating thermostat/programmer which I want to replace with a 'user friendly' Drayton Digitat 3.

I'm not sure on how to wire it up though. Currently I have a red wire, blue, yellow and earth.

On my new thermostat I have just 3 terminals (1 Common), (2 Heating Satisfied), (3 Call for heat). - can you tell me which coloured wire needs to go to these.

Thank you

 

[stem]

The usual method is:

Red = Live supply = Common

Yellow = Switched Live = Call for Heat

Blue = Neutral (not required on your new thermostat so insulate it and make it safe) Do not connect it to the remaining terminal.

Earth - Probably not required if the new thermostat is double insulated

This is the way the vast majority are wired, probably 99%, but you do get the odd rogue, so it can't be guaranteed. It's unlikely, but the original installer may have decided to use the yellow wire as the live supply, instead of the red for example.

If you post back which terminals the wires go on the original thermostat, someone will probably be able to confirm which is which.

 

[dmh1973]

Thank you very much Stem - appreciate your help. What you said looks correct according to the instructions. Just wanted to check - wasn't sure why the 2 terminal was there in the first place if not used!

Dean

 

[namsag]

The 2 terminal is there to supply power to motor off motorised valves , which are few and far between nowadays

 

[stem]

...or to operate air conditioning that has a cooling function, which is becoming more popular.

 

[danhiltonplumbingservices]

i have seen on some stats that the heat sat terminal 2 can be used for a little red light on the front of the roomstat/programmer so it comes on when boiler is on and off when it is off