Worcester Wiring Snag

[K1m]

Hi
I wonder if anyone can help me with the wiring of my boiler…………
Newish Worcester Greenstar 30CDI, new Horstmann programmer.
The boiler worked fine with all its power coming from the programmer – live, neutral, earth – these were the only wires to the boiler. Then the Bosch engineer came to fix a leaking air valve and mentioned in passing that the wiring was incorrect – the boiler should have its own connection to a fused mains supply. So I did that, but that left a problem with the programmer. I still only have the 3 core wire coming from the Horstmann but the Greenstar requires 4 wires –
from the manual: connect S junction box LIVE supply to terminal Ls
connect S junction box LIVE return to terminal Lr
connect S junction box NEUTRAL to terminal Ns
earth to earth

so what goes where?

S-plan, 3 zones + indirect water, all with 2 port valves.

all sugestions appreciated

 

[mogget]

I still only have the 3 core wire coming from the Horstmann but the Greenstar requires 4 wires –

Four core flex, or three core and earth cable

 

[K1m]

the picture in the manual shows only 3 core with no earth going to terminals marked:
Ls Lr Ns

the Horstmann is separately powered by a spur off the fused mains supply - not sure if this relevant

 

[snb]

just so i get this right.

you have a combi boiler with 3 zones and indirect hot water.

If so do the following.

connect live to live terminal
neutral to neutral
earth to earth

from wiring center connect ls(boiler) to junction terminal that has the orange wires from the 2 port valves.

the Lr should be the live supply to the wiring center
also the wiring center should have both the neutral and earths from the boiler connections only.

You shouldn't provide additional power to wiring center direct.

 

[mogget]

the Lr should be the live supply to the wiring center

I think on worcesters, Lr is the switched live (from wiring centre to boiler).

 

[K1m]

snb thanks, but...........I did as you said and the programmer isn't powered.
So I'll switch the Lr and the Ls as mogget suggests...........
I'll let you know
cheers
Kim

 

[h4gg13]

Ls means live supply from boiler to external controls, Lr is live return or switched live as has been said.
According to manufacturers instructions all external controls should be supplied from Ls on boiler pcb, so when on/off switch on boiler facia is at off you should have no power to controls or coming from controls to boiler.
refer to installation instructions.

 

[K1m]

thanks snb and mogget - problem now solved.

Haggis: none of your first para is mentioned in the instructions (user or installer) for either the Bosch or the Horstmann. Which installation instructions were you refering to?