Honeywell Sundial Plan Wiring Centre - Permanent Live - Nest

[Ray1000]

On my previous thread you kindly explained about the permanent live forth wire to an Ideal Logic Boiler at my son's house.

You'll remember I was concerned it may have been fitted on the input side of the isolating fused spur making it a bit too permanent.

While waiting for that to be resolved by the installers I had a look at the Wiring Centre today in readiness for fitting a Nest Thermostat.

At my own house where I fitted a Nest in February the Honeywell Wiring Centre is simply a box containing 10 connections. At my son's house it is an altogether more complex arrangement.

There seems to be 3 Blue, Red, Yellow, Green/Yellow and 1 Black, Red, Green/Yellow flat cables coming in along with the YPlan 5 core, the Cylinder Stat cable and the Pump Cable.

I could be mistaken but when the Fused Spur to the boiler and the MCB on the C/U were turned off there still appeared to be power in the box.

Q1. Can you help identify where all the wires come from ( I realise some are obvious) so I can end up with a diagram that includes the Google Heat Link and the Nest thermostat?

Also which part of the board is covered by the fuse?

The fused spur at the side of the boiler appears to have 7 wires connected to it.

Thank you
Ray

 

[CBW]

What are you using to prove power? Power could be coming from elsewhere.

Colours mean nothing in a heating system, as not all blues in that photo are neutral wires, some neutrals are black.

 

[Ray1000]

Thank you Chris, I had an ancient Trolex Deadline Indicator in my hand when I took the lid off ... it appeared to still be live.

 

[Ray1000]

Q2. Presumably the connections between the various cables are being made by a PCB when using a Sundial Wiring Centre ... Hopefully a Nest can still be wired into it?

 

[CBW]

ancient Trolex Deadline Indicator

That’s not suitable for proving dead. You need a 2 pole voltage indicator or a multimeter.

 

[CBW]

Hopefully a Nest can still be wired into it?

Yes, the Nest wires would be the same as the programmer wires. However, to use the existing thermostat wires you’d need to put the Nest near the wiring center.

 

[Ray1000]

I understand Chris, I only use it with caution.

 

[CBW]

I understand Chris, I only use it with caution.

Ok, that’s good. I use one for testing boiler cases, and sometimes it shows as live, but I haven’t had one that yet

 

[Ray1000]

Yes, the Nest wires would be the same as the programmer wires. However, to use the existing thermostat wires you’d need to put the Nest near the wiring center.

I was hoping to have the Heat Link on the ground floor near where the programmer is now and the Nest Thermostat adjacent to it using the 12v supply direct from the Heat Link.

I did this drawing before I realised the complexity of the wiring centre - there is obviously more to it than is shown here.

 

[Ray1000]

Q3. Does a Sundial board only have one LNE going to it at the bottom left and the other references are LNE going away from the board (In the case of the programmer for instance)

 

[Ray1000]

From Right To Left

1. Black cable from Y Plan to MID POSITION VALVE on board

2. From Cylinder Stat to CYL STAT

3. From Pump to PUMP

4. From Programmer to HW Off (Blue) HW On (Yellow) CH On (Red)

5. LNE going back to power the Programmer

6. LNE from Fused Spur to MAINS LNE on the board ... EDIT Plus yellow switched live from board to the boiler

7. EDIT 3 wires from the board to the room stat

 

[CBW]

Q3. Does a Sundial board only have one LNE going to it at the bottom left and the other references are LNE going away from the board (In the case of the programmer for instance)

Yes, all others are signal/switching wires.

 

[CBW]

From Right To Left

1. Black cable from Y Plan to MID POSITION VALVE on board

2. From Cylinder Stat to CYL STAT

3. From Pump to PUMP

4. From Programmer to HW Off (Blue) HW On (Yellow) CH On (Red)

5. LNE going back to power the Programmer

6. LNE from Fused Spur to MAINS LNE on the board

7. To the boiler ?? L L N E ?? From ??

View attachment 264603

I think 7 is your room thermostat

 

[Ray1000]

I think 7 is your room thermostat

I see, so the boiler seems to be oddly wired - at the time there was no need of the permanent live - the power to the boiler arrived in a light coloured three core flexible cable. There seems to be only one wire connected to the BOILER strip on the Sundial board.

 

[CBW]

It might only need switch live, rest might be at boiler?