Honeywell Sundial Plan Wiring Centre - Permanent Live - Nest

[Ray1000]

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

I'm sure you're right as the one wire on the board is clearly connected to S/L

 

[Ray1000]

Q4. Where might the three original wires to the boiler come from?

1. Yellow switched live returning in the mains power cable from S/L on the board must be connected to a three core flexible cable downstairs near the main fused spur.

2. Neutral wire on the three core flexible cable to boiler is connected to ???

3. Earth wire on the three core flexible cable to the boiler is connected to ???

 

[Ray1000]

Q5. If you had an Honeywell PCB wiring centre and a plain connector box to choose from which would you choose for your own house?

 

[Ray1000]

If the above diagram is correct I need to work out how to weave the Heat Link into it ...

 

[Ray1000]

It turned out the boiler is wired direct from the fused spur adjacent to it and the switched live is the only boiler wire coming from the wiring centre.

So I can better position the Heat Link for the Google Nest I need to extend the 5 wires plus earth to the existing programmer by less than a metre.

The colour are Black, Red. Blue, Yellow, Red and Earth.

The first single cable I found on the internet is 12v or 24v 7 core intended for caravan or trailer ... is it suitable for a central heating programmer?

 

[ianmcd]

It turned out the boiler is wired direct from the fused spur adjacent to it and the switched live is the only boiler wire coming from the wiring centre.

you are getting confused, the live wire from the fused spur is the permanent live, a switched live is a control wire that is switched by a control to signal something to operate.

So I can better position the Heat Link for the Google Nest I need to extend the 5 wires plus earth to the existing programmer by less than a metre.

The nest only requires an earth if you are using the 12v supply to power the thermostat.

The first single cable I found on the internet is 12v or 24v 7 core intended for caravan or trailer ... is it suitable for a central heating programmer?

Use 0.75mm2 5 core central heating cable, available to buy by the metre from many places

https://www.ebay.co.uk/itm/171794250654?hash=item27ffbc3b9e:g:8LgAAOSwgApXDM1C

 

[Ray1000]

Thanks to you Ian, I now understand the switched and permanent live.

I was trying to say that - rather than the live and neutral going from the fused spur up to the wiring centre then back down to the boiler along with the switched live - the feed to the boiler comes directly from the fused spur. They conveniently used 4 core cable to supply the power to the wiring centre so the extra yellow wire could return to the boiler as a switched live.

I intended using the heat link 12v power supply for the thermostat.

I was looking for a single cable having managed to make a small path through the dot and dab to where the Heat Link is going. (8mm dia 5 core passes through it OK)

I have some of the 5 core, but thank you for the link.

The answer has just occurred to me ... it is possible to remove the plastic "string" from 5 core cable and thread a earth wire through the centre making it "6 core" and use the appropriate sheathing on the ends for colour match.

 

[ianmcd]

You are doing it again, you keep talking about a Y plan system and a combi boiler system , in 2 different houses, if you ar talking again about the Y plan system , then the nest never tells the boiler when to fire, it tells the Mid position valve what to do, and the mid position valve controls the boiler, if you are bak talking about controlling a combi then your wiring pics are wrong

 

[Ray1000]

Sorry Ian, both houses are the same they have a Y Plan valve, Ideal Logic boiler, normal hot water tank.

I’m not sure what I’ve miss-said

Ray

 

[ianmcd]

Then the Nest does not in any way supply power to the boiler switched live, the nest supplies switching power to the mid position valve, the valve micro switches then tell the boiler when to come on

 

[Ray1000]

I have re-read all the above and I can’t see what I’m saying to the contrary.

I’m sure it will be me not using the proper electrical terminology.

 

[ianmcd]

you have a Y plan so remove the cover of the wiring centre, with the power isolated and post a pic of what is in there please

 

[Ray1000]

There is a picture of the Honeywell Sundial wiring centre on first page, first post.

 

[Ray1000]

If I am not mistaken ... replacing the British Gas UP2 Programmer wired to a Honeywell Sundial Wiring Centre with a Google Heat Link and Nest thermostat should be as follows?

 

[Ray1000]

Help required ... is it the case that all 4 wires on the Room Stat section of the Honeywell Sundial wiring centre need removing when a Google Nest is fitted.

I removed them when I did mine a few weeks ago but that was a simple wiring block rather than a PCB Sundial variety

Thank you