2 fuse spurs on a heating system

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gasman1987

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need some help sparkys i no we don't realy mix usualy as plumers and sparks but here we go lol

2 fuse spurs on the system, what u think?

vaillant with a vr 65 wiring centre (for all who don't no it is a wiring center with a pcb just plug and play) 1 fuse spur to power the boiler and 1 to power the vr65 and controls and they are interlinked via ebus


all i can do is lol and the customer don't want the floors to be touched so what can you do
 
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the reason i don't think it is right is

1 there is a differenc on the load of the circuit and fuse board if they are connected on different circuits

2 if you isolate 1 you realy don't think there is a secont fuse on the circuit

finding it hard nealy saying system not circuit



please comment
 
Do both spurs need to be off to make the relevant part safe, for instance, if you turn the spur off at the boiler, will the boiler still be live if the other spur is still on.

As for your idea about things being unbalanced, I dont quite follow.
 
i am under the inpretion the earthing on the fuse board are balanced with what side they are wired on the board 17th might be wrong


and the only thing that stops the boiler becoming live when the other is isolated is a pcb that cauld malfunction the 2 circuits are interlinked with 2cables


i don't think it is right
 
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Yes, the Vaillant boiler needs a permanent supply as does the VR65 WC: but the two must only be supplied by a single source.

This can be achieved by looping the boiler feed from the VR65 terminals (which are rather small for taking two 0.75mm flexes) or by running two flexes from one common FCU.

But the boiler and WC mustn't be fed from separate sources!



Lucia.
 
And, what on earth do you mean that the two FCU's are inter-linked by E-Bus connections?

The 24V E-Bus connections are between the VR65, the boiler and any optional Vaillant 'stat - but never between 230V accessories!

Lucia.
 
PrinceofDarkness said:
And, what on earth do you mean that the two FCU's are inter-linked by E-Bus connections?

The 24V E-Bus connections are between the VR65, the boiler and any optional Vaillant 'stat - but never between 230V accessories!

Lucia.
Click to expand...



yes that is what i mean the ebus connections of both units
 
PrinceofDarkness said:
Yes, the Vaillant boiler needs a permanent supply as does the VR65 WC: but the two must only be supplied by a single source.

This can be achieved by looping the boiler feed from the VR65 terminals (which are rather small for taking two 0.75mm flexes) or by running two flexes from one common FCU.

But the boiler and WC mustn't be fed from separate sources!
Click to expand...

Lucia, why ever not? I've never fitted these controls, but the VR65 installation instructions seem to suggest that the E-bus wiring between the boiler and control centre is all ELV.

If this is indeed the case, I can't see any major harm in feeding the two from different sources, as even if someone working on the equipment didn't realise there were two points of isolation, it seems unlikely they would come to any harm. Perhaps not ideal, but not dangerous.

If the wiring shared between the boiler and control centre were 230v, that would be a different matter.
 
there is a potential risk i would have thought that the connectyions could become 230v if there was a malfuntion with the pcb's
 
gasman1987 said:
there is a potential risk i would have thought that the connectyions could become 230v if there was a malfuntion with the pcb's
Click to expand...

By that logic, the same thing could happen should there be a serious malfunction in your mobile phone charger, causing the pins on the charger plug to become live at 230v. That doesn't mean you put on a pair of rubber gloves every time you use it.

In this case, it's more than reasonable to design and install on the basis that the equipment will operate as it is designed to do.
 
Matthew: perhaps you've misunderstood the situation?

I'm saying that an ordinary domestic heating system should only be fed from a single LV circuit.

The issue of the E-bus ELV terminations is pretty much a red-herring here, as such a connection is never introduced into a FCU (or two in this case).

The E-bus connections are strictly between the boiler, the WC and the optional Vaillant 'stat. They have nothing to do with the supply FCU which should be a single unit.


Lucia.
 
i take your point but in my head i think it would be more professional to have the 1 spur to feed the 2 boiler and wc


you make a fair point though
 
PrinceofDarkness said:
Matthew: perhaps you've misunderstood the situation?

I'm saying that an ordinary domestic heating system should only be fed from a single LV circuit.
Click to expand...

It usually is, but it doesn't have to be, as long as the interconnections are made in such a way as to prevent injury to someone, somewhere down the line who otherwise wouldn't be aware that there are multiple points of isolation.

It should also be done in such a way that one circuit could never feed the other, which is already inherently taken care of by the design of the VR65 and the relays it contains.

EDIT: From the VR65 manual:

Note! The VR 65 requires a 230 V supply. The ecoTEC boiler also requires a 230 V supply. The eBUS wiring between the two will not provide 230 V from one device to the other!

...

The Control Center VR 65 requires its own 230 V mains supply via a switched fused spur. The boiler also requires a 230 V supply.
Click to expand...

PrinceofDarkness said:
The issue of the E-bus ELV terminations is pretty much a red-herring here, as such a connection is never introduced into a FCU (or two in this case).

The E-bus connections are strictly between the boiler, the WC and the optional Vaillant 'stat. They have nothing to do with the supply FCU which should be a single unit.
Click to expand...

Eh? One of us here has certainly misinterpreted the OP, which isn't surprising given his style of writing! The E-bus connections do not go anywhere near the FCUs. All the OP states is that the wiring centre and boiler are supplied through separate FCUs, with ELV E-bus wiring inbetween.

Next you'll be telling me that we can't have networked linked computers unless they're all plugged into the same extension lead... :LOL:
 
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