Circuits needed for boiler controls?

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Hello all,

I am in the middle of a house renovation and need some help on circuits for the boiler controls.

We currently have a sparks in doing 1st fix but he has said that he doesn't get involved in the heating controls... Which is fair enough.

He is happy to run wires etc.

What do I need?

I am getting him to run a 3 core and Earth to the external boiler (live and switched live needed), also 3 core and earth to the stat. SFCU in the airing cupboard for power.

Anything else?

I'm also a little confused what I need boxes wise in the airing cupboard.

I'm guessing twin and earth from SFCU to timer, 3 core and earth from timer to wiring centre, cable from boiler and stat, zone valve etc (will be Y plan) to wiring centre?

Thanks in advance.
 
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You need a 240V supply to the wiring centre location and the relevant cables from there to the boiler and all of the accessories.
 
assuming you have a tank

Usually 2 lots of 3C+E to the airing cupboard.

1 for the tank stat
1 for the 3 port valve
 
Check the wiring diagrams for the heating system.

Most common are Y plan or S plan.

Often the three port valve will require 4 core + earth and this can be most tidily installed using 5 core flex to the wiring centre ( junction box )
 
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I've had a bit of a read around and I think I'm sorted.

Thank you all.

Just needed to get my head around what I needed sunk in the wall and what can be run externally, for neatness really.
 
We currently have a sparks in doing 1st fix but he has said that he doesn't get involved in the heating controls... Which is fair enough.

.

Not being funny, but any electrician worth their salt should be able to wire a simple heating system like this. :rolleyes:
 
3 cores from switched fused connection unit.

5 cores to boiler

6 cores to programmer

4 cores to room stat & frost stat

5 cores to each 2 port zone valve

6 cores to 3 port zone valves

4 cores to cylinder stat

3 cores to pump

All run back to a wiring centre somewhere convenient and accessible.

All wires above include one core as earth.

Use either 0.75mm² or 1.0mm² cable.
 
3 cores from switched fused connection unit.

5 cores to boiler

6 cores to programmer

4 cores to room stat & frost stat

5 cores to each 2 port zone valve

6 cores to 3 port zone valves

4 cores to cylinder stat

3 cores to pump

All run back to a wiring centre somewhere convenient and accessible.

All wires above include one core as earth.

Use either 0.75mm² or 1.0mm² cable.

Thanks,

Why 5 cores to the boiler? Boiler supply only needs 4,
Live
Switched live
Neutral
Earth

Will need to check frost stat but as its an external oil, I'm sure it has one built in.

6 cores to programmer... 7?
 
Some boilers send a pump over-run signal back to the wiring centre, so need another core for this.

Programmer needs L,N,E and three switch lives back to the wiring centre if you have a Y plan setup.

Stick with what I've said and you'll be good to go. If you end up with an odd extra core it's no great problem. If you end up one core short somewhere it could be a huge pita.

One other thought, as it's an external boiler, do you need power for trace heating to the boiler, pipework or condensate drain?
 
Some boilers send a pump over-run signal back to the wiring centre, so need another core for this.

Programmer needs L,N,E and three switch lives back to the wiring centre if you have a Y plan setup.

Stick with what I've said and you'll be good to go. If you end up with an odd extra core it's no great problem. If you end up one core short somewhere it could be a huge pita.

One other thought, as it's an external boiler, do you need power for trace heating to the boiler, pipework or condensate drain?

I was meaning another earth :p lol

The boiler doesn't have a 5 terminal but I will double check the boiler wiring diagram.

The boiler hasn't been touched and doesn't have trace heating, never considered it tbh, worked ok before I'm guessing!!
 

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