Central Heating Wiring

renard · 23 Mar 2010

Looking for some help.

I have got a two 2 port Zone S-plan central heating system.

Looking at standard wiring diagrams, the orange cables from the two valves connect to the SL boiler and L pump.

On my system my two orange cables attach to a white wire only, which gets power from the orange cables.

The SL (I assume) and the pump live are only attached to each other.

Using a multimeter, when the orange cables get powered, the signal goes through the white wire which then connects (somehere - not in the wiring centre) to the SL which in turn powers the pump.

My question is what is this white wire connected to the valves all about?

Andygasman2010 · 23 Mar 2010

What boiler do you have? Make/model

renard · 23 Mar 2010

It is a Potterton Suprima 40.

Andygasman2010 · 23 Mar 2010

The orange wires should go to the SL on the boiler only. The pump should be fed directly from the pump live on the boiler. This is important as it can cause the boiler to lockout.

Where does the white wire/s come from? The system or the zone valves?

matt1e · 23 Mar 2010

renard said:
Looking for some help.

The SL (I assume) and the pump live are only attached to each other.

Using a multimeter, when the orange cables get powered, the signal goes through the white wire which then connects (somehere - not in the wiring centre) to the SL which in turn powers the pump.

My question is what is this white wire connected to the valves all about?

I don't really know what you are asking here
the pump will or should be connected to the boiler pump terminals not directly to the S/L as the boiler has a pump over run facillity
and i would think the white wire connected to the valve oranges would be connected to the boiler S/L terminal but in your statement above it seems as though you know this already! so as I say I don't really know what you are asking

Matt

renard · 23 Mar 2010

The white wire comes from the system, not the valves.

My confusion is that the actual wiring doesn't look like the wiring diagrams I have seen.

Andygasman2010 · 23 Mar 2010

renard said:
The white wire comes from the system, not the valves.

My confusion is that the actual wiring doesn't look like the wiring diagrams I have seen.

A standard S-plan wiring diagram will probably show the pump fed from the orange wires on the valves. With your boiler it MUST be as i described earlier. Your system won't necessarily look like the wiring diagram you are working from.

Central heating wiring isn't always colour coded very well so the fact that the wire is white isn't that important (unless it comes from the valve, which you say it doesn't) Where does this white wire go?

It sounds like the white wire will go to the SL on the boiler

Do you have any faults? Why are you looking into it?

matt1e · 23 Mar 2010

renard said:
On my system my two orange cables attach to a white wire only, which gets power from the orange cables.

then

renard said:
The white wire comes from the system, not the valves.

renard said:
My confusion is that the actual wiring doesn't look like the wiring diagrams I have seen

my confusion stems from the two seemingly contradictory statements you have made ,but to answer the later part sometimes the pump is connected to the wiring centre s/l, sometimes it is connected to the boiler directly and sometimes it is connected directly to the boiler VIA spare terminals in the wiring centre,as well as this different installers use different core colours and numbering schemes, all this can cause confusion as you have found
does your system work ok?

Matt

renard · 23 Mar 2010

I am looking at it because a temporary fix was made to it at Christmas so that when the hot water came on, the heating would also come on.

The fixer, not me, said there were not enough wires, and has put a 'jump' between the brown hot water wire and the brown central heating wire and taken the central heating thermostat out of the 'loop'.

I am trying to work out what all the wires do inthe wiring centre to get the hot water and heating running independantly now summer is coming.

Andygasman2010 · 23 Mar 2010

hmm doesn't sound possible to assist you on here. like i say, colour codes aren't universal.

Do you have the installation instructions for your boiler? there will be a wiring diagram in there.

matt1e · 23 Mar 2010

renard said:
I am looking at it because a temporary fix was made to it at Christmas so that when the hot water came on, the heating would also come on.

The fixer, not me, said there were not enough wires, and has put a 'jump' between the brown hot water wire and the brown central heating wire and taken the central heating thermostat out of the 'loop'.

I am trying to work out what all the wires do inthe wiring centre to get the hot water and heating running independantly now summer is coming.

can you post some photos of your wiring centre (with the cover off)renard? it would be a great help, you have a multimeter so thats a bonus too!
also why was the room stat disconnected?

matt

tamz · 24 Mar 2010

renard said:
I am looking at it because a temporary fix was made to it at Christmas so that when the hot water came on, the heating would also come on.

The fixer, not me, said there were not enough wires, and has put a 'jump' between the brown hot water wire and the brown central heating wire and taken the central heating thermostat out of the 'loop'.

I am trying to work out what all the wires do inthe wiring centre to get the hot water and heating running independantly now summer is coming.

So you have a sticking microswitch on the heating valve and could have been easily fixed at the time.
If your heating was working as it should before christmas (hw and ch independant of each other) and boiler was not locking out, the wiring is fine and your guy just could not follow it. Heating systems can be (are) wired up in dozens of different ways with whatever coloured switch wires turned the original fitter on.

Just remove the link and put cyl stat wires back where they were and all will be fine.
OH and fix the heating valve.

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Central Heating Wiring

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