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.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.