Installing a room thermostat

Associate
Joined
13 Aug 2005
Posts
166
Anybody good with electrics?

im looking to fit a wireless room thermostat and receiver to my combi-boiler

the instructions for my combi say to remove the link wire and replace it with wires that go to the receiver

now the instructions for the receiver state

1 NO Normally Open [N/O]
2 COM Linked Live feed (230V AC heating applications only)
3 L Live feed (230V AC)
4 N Neutral

am i correct in saying 3 and 4 are the power from the mains (or boiler if piggy backed)?

and if 2 (COM) is linked to 3 (Live) that only leaves me the number 1 empty so what other wire goes into the old link on the combi?

thanks
 
Associate
Joined
15 Nov 2005
Posts
2,245
Location
Newcastle
You don't link terminals 2 and 3 at the receiver.

3 and 4, as you thought are for the mains power in. Terminals 1 and 2 get wired back to the terminals on the boiler that you removed the link wire from.

All the receiver does is make that link when you have heating demand, and break the link when there is no demand.
 
Soldato
Joined
10 Mar 2006
Posts
2,890
Location
Fife
A common terminal basically takes whatever voltage you apply it and switches that. Hence why it says link live if your boiler needs 230v switching.

You need to check your boiler and see what voltage it switches at. If you put 230v down a 12/24v line it'll blow up your PCB. If you put 12/24v down 230v it won't switch.

Some boilers also require 2 terminals for call to heat. Others only require one. Really need your boiler manual to be honest.
 
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