replace boiler's mechanical clock with thermostat

[andyinglasgow]

Hi all. This is a very specific question which feel sure should be answered somewhere, but I have been unable to find it, so please excuse any redundancy. The situation is that I have a Volkera 25 compact boiler, the manual to which can be found at:
http://cdn0.vokera.co.uk/wp-content/uploads/2013/11/Compact-A-User-and-Installation-manual.pdf

This currently has a mechanical clock attached (connection detailed on pg 31 of the manual). A picture of the connection is attached - there are 4 wires, brown, blue, red and black (which does not seem to match with what the manual tells me, but perhaps I am misunderstanding...)

The manual then lists programmable thermostats as a typical control application, and provides the wiring diagrams on page 31. I now want to install a Nest thermostat, whose guide can be found at:
https://s3.amazonaws.com/support-as...ges/Nest-Thermostat-Installation-Guide-UK.pdf

Without any further ado, the question then is: what wires go where? Thanks!

 

[jackthom]

Basically the boiler fires for heating when the red wire is connected to the black wire in that connector.

So you can unplug the timer then safely extend the boiler red wire to connect into terminal 2 in the Nest Heatlink and extend the black wire to go into Heatlink Tertminal 3.


The timer connector also carries mains voltages (which you will no longer be using) so it will need to be made safe, making it impossible for anyone to accidentally touch the brown/blue terminals or for them to come into contact with other parts of the boiler.

 

[muggles]

Brown to Nest L, Blue to Nest N, Red to Nest 2, Black to Nest 3

 

[andyinglasgow]

Fantastic! What a great resource! I understand the red/black now - the only inconsistency is whether the brown/blue terminals need to go in the Nest as well, as muggles says (and the manual seems to agree with, based on my limited understanding), or if the Nest will get whatever power it needs from the red and black without need for the mains voltage, as jackthom seems to be implying. Thanks again.

 

[jackthom]

Sorry to cause confusion. The Heatlink does need mains power and muggles idea of using Brown and Blue to supply that is a good one.

 

[andyinglasgow]

All right then - I am good to go! Will put it in tomorrow. Thanks again

 

[andyinglasgow]

Worked perfectly!