Help connecting a Wireless Room Stat to a Combi Boiler

[Tony99]

Hi,

I have moved into a house with a Potterton Lynx 2 Combi Boiler connected with 2 wires to an old wall mounted room stat located in the coldest part of the house. I would like to move this and think that the simpliest way would be to disconnect this and install a new wireless room stat that I can take into the front room.

I have been looking at either a Siemens RDH10RF or a Drayton Digistat RF. Both of these seem to have the same basic wiring connections into the SCR:

L - live
N - neutral
1 - common
2 - heating satisfied
3 - call for heat

Connections 1,2 and 3 are the switch control and the diagram shows connections into the boiler control from 1 and 3.

My question is that on the boiler control for the thermostat there are 4 connections.

SWL - switch live
L - live
N - neutral
Earth

I understand that for these stats you dont need to connect the earth and obviously the live and neutral connect to each other, but where do connections 1 and 2 run to, I seem to be a wire short?

I'm sure theres a simple answer to this and hope someone can put me out of my misery

Thanks in advance,

Tony.

 

[bookahandyman]

Your rf receiver will have live, neutral,satisfied and call. live and neutral are obvious and you can take these from your boiler power source or elsewhere. the call No 3 will go to the switch live of the boiler. ignore no 2.
i reccomend the honeywll cmt927 rf it is very easy to wire and use/program. you do have to link a few terminals together with the live in the reciever but very easy to do.

 

[Tony99]

Many thanks for the quick reply Bookahandyman.

So I connect the SWL to 3 and ignore 2, but where do I run the wire to from the connection marked as '1-common'?

Thanks for the recommendation on the Honeywell, I'll look into that.

Sorry to be a pain.

Tony.

 

[bookahandyman]

check the live on the boiler and see if it is sending 240v or if it is waiting for 240v ,some boilers have a live to power an external timeclock and a swl. so if its 240v then connect the common to the live on boiler, 3 to the swl and see if it works if not then the live on the boiler is an input not output so link the live and common on the rf reciever.

 

[Tony99]

Ok many thanks for the response, I think I understand.

I read on another post on this forum that within the RF unit you needed to connect the other end of the switch connection (connection 1) with a short wire into the live. This doesn't quite sound right to me, if the connection was required, why does the unit not already come with this connection?

Tony.

 

[bookahandyman]

thats what im trying to explain by linking 1 with the live, but on your diagram it should come from the live on the boiler wiring for the stat which is the live for the clock now, and the call to the second connection which is the stat wire call now.most modern combis just have one swl and then you have to introduce the live to the other side to complete the loop.