Blonde moment CH wiring (y plan + ecotec boiler)

Chri5 · 21 Jan 2011

Having the new boiler fitted on Sunday.

The existing system has a FCU adjacent to the programmer unit and that feeds on to the boiler down stairs.

So the plumber has asked for a FCU at the boiler location and intends to use the existing 3 core + earth between the boiler and y plan box.

So looking at the diagram

and then considering the Vailant eco tec wiring block

Untitled

Chri5
21 Jan 2011
1

What goes where ?

LearningSpark · 21 Jan 2011

Your new fcu at the boiler will give you your permanent l,n & e. Termial 8 from your wiring centre will go to terminal 4 on the boiler (switched live). You will then need to remove your pump feed from terminal 8 of your wiring centre and feed the pump from the pump output on the boiler. This will be so your boiler controls the pump for the pump over run. I hope this makes sense, if not I am sure someone will be along who can explain it better.

spraggo · 21 Jan 2011

Spot on LearnerSpark other than the OP needs to remove the link between 3 and 4 on the boiler block.

spraggo

londonboy · 21 Jan 2011

I think you will need more than a 3 core and earth between boiler/prog and cylinder cupboard

I make it 6 cores + cpc.

ELZ4742 · 21 Jan 2011

just be aware that most new boilers will insist on..

PERM LIVE
SWITCHED LIVE
BOILER NEUTRAL
CPC
PUMP LIVE
PUMP NEUTRAL
CPC

You may invalidate the warranty if the pump neutral is shared and not a dedicated one. Rediculas but true.

Chri5 · 22 Jan 2011

londonboy said:
I think you will need more than a 3 core and earth between boiler/prog and cylinder cupboard

I make it 6 cores + cpc.

Why- are you suggesting discon of the existing LNE at the wiring centre and bringing the LNE up from the boiler. then the pump controls from the boiler and then the switched live via boiler terminal 4 ?

The new FCU at the boiler was / is going to be terminated at the CU on the same MCB / rcd rail as the existing LNE to wiring centre to prevent shared neutral issues.

flameport · 22 Jan 2011

Boilers and controls should be supplied from a single FCU, as the diagram from the boiler manufacturer shows.

Therefore if positioning the FCU next to the boiler (which is where it should be), the other one is removed.

spraggo · 22 Jan 2011

Chri5 said:
The new FCU at the boiler was / is going to be terminated at the CU on the same MCB / rcd rail as the existing LNE to wiring centre to prevent shared neutral issues.

The pump has to have it`s own dedicated permenant live via the pump over run switch on the boiler.

spraggo.

bernardgreen · 22 Jan 2011

Do the regulations permit the use of 7 core YY cable in this situation ?

RF Lighting · 22 Jan 2011

I can't see why not.

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Blonde moment CH wiring (y plan + ecotec boiler)

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