Greetings. I am wishing to replace my ancient room thermostat with
Horstmann digital 7 day type. My old thermostat has four wires, earth plus a red, yellow and a blue. The Horstmann unit is looking for tw connections although it has three connections available, NO, NC, COM Can someone tell me how I should proceed?
Cheers. John
-- Biggooner
Your new stat doesn't require an earth *or* a neutral - only a live and switched live. You really need to check out what the other end of the cable connects to - but it's a reasonable bet that you need to connect red to COM and yellow to NC - with nothing being connected to NO. [The NO contact is only used when you're controlling a *cooling* rather than heating system].
Make sure the unused (blue and earth) cores are well insulated and secured out of the way.
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