Wiring a 30cdi Conventional S Plan

[minion]

Hello,

Was hoping for a little advice if possible.

We are fitting a regular 30cdi boiler to replace an old one and I am fitting a new pump, valves and programmer etc.

Nearly all we fit now are combi boilers with plug in clocks so its been a while since I have wired anything up myself.

I have no issues with the s plan wiring as that is really simple. I will be connecting the pump to the boiler for pump overrun so that is fine.

What I am unsure of is the actual terminal on the boiler itself. There is a live netual and earth from the spur but from the wiring centre it says there is a Live supply to terminal (ls) live return to terminal (lr) and netral to terminal box(ns)

I only have one switch live from either of the orange wires so am confused as to where to connect it.

If anyone could help id appreciate it. Obviously I can call Worcester in the morning but it is doing my brain in tonight.

Thanks

 

[holty]

lr

 

[ianniann]

Usually wire a standard mains supply to the live/neutral/earth. Then you would remove the jumper between Ls and Lr, take Ls (and maybe Ns) for the live supply to your controller and return the switched live to Lr. Many electronic controllers will also require an internal link from the Ls connection to an additional live input.

 

[DP]

OP, if I was going to S plan your boiler and wire it too, I would remove the link and connect the grey and orange across the terminals where the link came out.

The link is what fires the boiler. Remove the link the boiler goes off. Live neutral and earth are needed to power the boiler for pump over run, frost protection etc, but link is what tells the boiler to get out of bed and start shovelling coal.

Making one of the auxiliary terminals live was ok for boilers of Thatcher era but if done on modern boilers can leave part of the boiler circuit at live potential when boiler switched off. There are boilers on which one of the auxiliary switch wire can be sourced from elsewhere but what is the point. One of the terminals will be at 240 anyway, but sometimes it can be at low voltage (application of 240 will then fry the board). Treat all boilers with a link as needing to be fired by voltage free contacts

 

[namsag]

As DP says orange and grey in place of the link

 

[D_Hailsham]

OP, if I was going to S plan your boiler and wire it too, I would remove the link and connect the grey and orange across the terminals where the link came out.

There would be two greys and two oranges (heating and hot water) connected to the boiler, which is a bit messy. Or were you thinking of running a twin cable from the wiring centre's orange and grey terminals?

 

[DP]

DH, I am a little surprised you have written the post asking if the two orange and two greys will be taken to the boiler direct. No sane person in his right mind would do that.

A sensible person would have an independent channel programmer (or a timer and a progstat for control) fitted where desired, cabled to a wiring center with an appropriate cable (3 or 4 core) or (5 core cable if a programmer is fitted). Then he would wire the zone valves to this common point and take a 5 core cable, even 6 core if needed to the boiler from the wiring center. This is the way I would do it.

 

[D_Hailsham]

I'm glad that you are both sane and sensible! The way you described it initially brought that into doubt.

 

[DP]

The way you described it initially brought that into doubt.

Afraid not dear chap, have you seen the length of the cable attached to the diverter? One would have to be a magician to remove the grey + orange conductors from the cable and slap these onto loop termination in the boiler.

 

[D_Hailsham]

Afraid not dear chap, have you seen the length of the cable attached to the diverter?

Yes.

One would have to be a magician to remove the grey + orange conductors from the cable and slap these onto loop termination in the boiler.

It depends on the relative locations of the components. There is no reason why the pump, valves etc should not be located adjacent to the boiler.

 

[namsag]

You are just being an ar5e now. even if components where close to the boiler the flex would have to be stripped back a minimum of twelve inches and is it allowed to have just a single wire this length unprotected , i think not.