Combi Room Stat+Timer Sanity Check on wiring

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This relates to a Ravenheat CSI85A
Wiring diagrams shown here:

fig95:
View media item 56496fig48:
View media item 56490fig94:
View media item 56491
Anyways, the boiler has a 7 day timer integrated and a basic room thermostat downstairs (i.e. one with a simple temperature dial)

I want to get a Wireless roomstat which I hope will control both temperature and timer
e.g. Honeywell 927 as an example.
http://www.honeywelluk.com/products...tats/Wireless-Programmable-Thermostats/CM927/

with a wiring guide of:
View media item 56492
As the diagram is not identical to my boiler, I wanted to get confirmation that what I plan to do is OK:

Wire the connection that says 'Room Stat' on my boiler to A and B on the honeywell BDR91.

Wire the connection that says 'Timer ' L/N on the boiler to L/N on the BDR91 (on the boiler, L and N are directly connected on that connector).

My assumption is that as my boiler has a separate L/N for the timer, I do not need to put the BDR91 in line with the incoming power as shown in the honeywell diagram.

I am mildly concerned about the other two wires from the original clock circuit - they go across to the same place on the PCB as the roomstat connection. They are the ones labelled 'gr'.

Also, on both wiring circuits, the Room Thermostat connection is linked out. I definitely have a piece of white PVC T+E that is connected and goes to the downstairs (the E is not connected to anything, to reassure you). So I'm wondering that if the 'Room Thermostat' and Timeclock switches are used, then it must be configured as a logical AND... and in that case, I need to either link across the 'Room Thermostat' connection (as they have done in the wiring diagram) and use the Connector that serves the Timeclock, or vice-versa.

Does this make sense? Sorry if it seems overcomplicated :)
 
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The link you talk of is installed at the factory so the boiler will run without any external controls fitted.

If you want to install a room stat for example, you remove the link and connect the stat in it's place, so rather than the boiler running all the time, it only runs when the stat calls for heat.

I'm not a plumber, so I'm not familiar with your boiler. Is there an option on your built in clock to over-ride it onto permanantly on? If so, it will be easier to just set it to this, rather than trying to remove it and bypass the wiring for it.

What type of wiring, and how many cores including earth do you currently have from the boiler to your existing stat position?
 
Wireless receivers require a mains supply to operate, - this can usually be taken from the fused switched outlet which supplies power to the boiler. The honeywell receiver terminals A and B don't have their own voltage - they are connected to the terminals for the roomstat on the boiler (where the factory link can be fitted). The boiler will provide the switching signal voltage (whatever that might be) through the honeywell's contacts. Once your new programmable stat is installed, leave the integral boiler timer to permanently on, and the programmable roomstat will do the switching. The honeywell receiver unit basically takes the place of the old roomstat, but obviously needs its own power to be a radio receiver.
 
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OK thanks for the input.
So the concensus is to leave the existing timer as-is, and to simply replace the room thermostat with the new roomstat base unit - drawing power from the main boiler power.
Thank you!
 

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