Nest 3rd generation Thermostat and C-Plan system

[Echo the husky]

Oh look, more terrible central heating wiring!
Is it me or is the 3 core flex to the programmer redundant as it is doubled up with the 5 core flex?

Is that diagram correct? I would have expected a blue wire in cable 1 not cable 2.

 

[abel88]

Right, here's a picture of the motorised valve on the pipe, i can't tell you what pipe it's on as i have no idea what pipes are what. Also pictures of other pipes from the boiler.

Also there are only 5 cables coming from the motorised valve as shown (the bottom set of wires in the pic, it is then joined to another distribution block and then on to the junction block as per previous diagram) I've also included a picture of the model of the valve.


Lastly a picture of the cylinder thermostat, there is also on the a cylinder pipe a zone valve actuator. Last picture shows the actuator wiring being joined to the wiring of the cylinder thermostat (i haven't yet determined what is joined to what) which then goes down to the boiler room. I have no idea what the zone valve actuator does to be honest. the whole system seems a mess but it appears to function, correctly or not I don't know...

 

[Johnmdc]

So your saying now that there are 2 motorised valves? If that is the case then it is a S plan system.

 

[Agile]

Why not just connect the Nest two wire ( com and call ) output in place of the room stat for the moment and put your programmer onto 24 hr heating on?

Then at least you can have all the fun of the Nest.

Later you can see if you can sort out your wiring mess and if there are really two zone valves then rewire it at your leisure as a conventional S plan and ultimately connect the Nest water connections.

With that wiring mess it may be easier to just move house!

Tony


Edited to correct to S plan!

 

[shambolic]

S plan Tony, S plan if he has 2 zone valves.

 

[abel88]

Why not just connect the Nest two wire ( com and call ) output in place of the room stat for the moment and put your programmer onto 24 hr heating on?

Then at least you can have all the fun of the Nest.

Tony

But doesn't the nest heatlink need to be installed for the thermostat to work? Is that what you're suggesting?

 

[abel88]

I have edited your wiring diagram to show how the Nest should be wired.

View attachment 91967

Seeing as the current systemnis working, would wiring the heatlink as suggested above just work fine?

 

[Johnmdc]

Just put the heat link in place of your existing clock!!

 

[Johnmdc]

How many valves have you got?

 

[Agile]

When I say Nest, I mean the Heatlink part which is the interface to the system.

As suggested once the wiring has been checked/corrected then the Nest can be wired in place of the programmer.

But at the present knowledge and understanding of the system it might be better not to try to be to advanced and just connect it in place of the room stat ( which is basically what the Nest is ).

Tony

 

[abel88]

Tony, sorry I'm confused, do you mean remove my existing programmer and install the heatlink in it's place with the same wiring (live, neutral and earth then connections for call for heat and water) and just replace the room thermostat?

 

[abel88]

How many valves have you got?

2 looks like, one on a pipe coming from the hw cylinder and one by the boiler

 

[abel88]

Ok, if looked at the wiring instructions for the drayton zone valve here:
http://www.draytoncontrols.co.uk/WorkArea/DownloadAsset.aspx?id=10510

and my wiring diagram is beginning to make a bit more sense now. I think some of the confusion here is some of the cables have been joined/replaced with different coloured cables. Just want to know if safe to wire as is to nest heatlink.

Many thanks for everyones time.

 

[Echo the husky]

Just want to know if safe to wire as is to nest heatlink.

Well as the wiring is very poorly installed and does not meet the minimum requirements of the wiring regulations, I'll say no, it is not safe to wire it as it is.

I would strongly advise calling an electrician to properly re-install all the heating controls.

 

[abel88]

Hi all,

Just to say i've sucessfully managed to install the Nest Thermostat just fine (was pretty easy actually) and everthing is working fine.

Thanks to all those that helped, much appreciated.