24v thermostat

[Lectrician]

Page 26 does give a diagram showing the three 24v cables. However to see how these are used one has to look at this PDF and it would seem the 24v supply is all connected with the ebus and uses a VR30 board.

This it would seem changes the speed of the pump and is rather complex and I would not want to mess with these connections.

I have the same boiler - The sbus supplies power and data over two conductors. The 3 '24v' terminals clearly show "Do not use". The sbus can control many things, and also reports other things to the remote screen, such as icons for pump run, flame lit etc. Quite good really.

 

[Lectrician]

An interesting diagram.

So the thing has a single connection to zone valves, programmers, room thermostats and cylinder thermostats?

All of which also have a permanent live?

There are 240v terminals to power your external controls, putting a live supply to terminal 4 fires the boiler, this could be simply via a thermostat, or via valves etc if zoning required. Terminal 3 and 5 provide a 230v source (3) and a neutral (5).

 

[ban-all-sheds]

Ah - sound of penny dropping

A diagram which has nothing to do with a Nest

 

[feridoun]

Hi everyone,
Just wanted to share that I got my Nest thermostat working with a 24v transformer and 24vac relay using the following wiring. My boiler is a Vaillant Ecotect plus 837. http://imgur.com/JjHJQq2 .

Thanks for the advice on the board.

 

[feridoun]

Further good news today - the Nest now accepts a UK postcode