Boiler Supply Q

[wundaboy]

The plug/FCU thing seems to be regional.

I live between two places - in Swansea, the RGIs swear blind that only a plug and an unswitched socket is acceptable, whereas in Shropshire they swear blind that it can only be an FCU.

 

[JohnW2]

In my (limited) experience, they still think the instructions require an FCU and no other option.

If they "thought" that in relation to the Worcester one whose instructions eric posted, that would presumably mean that they couldn't even read, let alone being capable of dealing safely with the electrics of a boiler ...

Kind Regards, John

 

[oldbutnotdead]

If your heating setup has any mains powered bits and bobs (motorised valves, timeclocks/programmers/wireless base stations in different rooms) try very hard to make sure they're all powered from the same circuit-avoids problems with borrowed neutrals and devices being unexpectedly live.

 

[SimonH2]

If your heating setup has any mains powered bits and bobs (motorised valves, timeclocks/programmers/wireless base stations in different rooms) try very hard to make sure they're all powered from the same circuit-avoids problems with borrowed neutrals and devices being unexpectedly live.

Not just "a good thing to do", but also a specific requirement from BS7671 in a domestic environment. "The" isolator must isolate the whole system.

 

[bernardgreen]

For what it is worth,

My mother's last house built mid 1990's had a boiler in the ground floor kitchen and a hot water cylinder with pump and valve gear in a first floor airing cupboard.

There were two double pole switches connected in series for the supply to the heating system. One by the boiler and one in airing cupboard and both had to be on for system to work.

 

[RandomGrinch]

If your heating setup has any mains powered bits and bobs (motorised valves, timeclocks/programmers/wireless base stations in different rooms) try very hard to make sure they're all powered from the same circuit-avoids problems with borrowed neutrals and devices being unexpectedly live.

Not just "a good thing to do", but also a specific requirement from BS7671 in a domestic environment. "The" isolator must isolate the whole system.

Thanks, that was my understanding of the 'preference' for an FCU, as it can provide larger terminals for the connection of additional wiring for the controls, if there is no junction box, or if the boiler power connections are unsuitable.
As well as providing a very important single point of isolation.
It is also the method suggested in some installation guides for Nest etc.

 

[SimonH2]

At one time it seems it was common for boiker MIs to specify "a double pole isolator with 3mm contact gap" (which many read as meaning an FCU) or even be as specific as saying FCU. I suspect they've adapted to requiring a means of isolation (without specifying what that must be) - both in resoonse to queries/complaints, and to make the manuals more generic (less country specific licalisation).

 

[JohnW2]

At one time it seems it was common for boiker MIs to specify "a double pole isolator with 3mm contact gap" (which many read as meaning an FCU) or even be as specific as saying FCU. I suspect they've adapted to requiring a means of isolation (without specifying what that must be) - both in resoonse to queries/complaints, and to make the manuals more generic (less country specific licalisation).

I'm not so sure about "less country-specific localisation".

A problem with boilers (and a good few other things) is the requirement in MIs for ...

(from the Worcester MI posted by eric, but very common).

My understanding is that not only do very few countries outside of the UK have fused plugs, but nor do they really have any equivalent of an FCU (other than large 'switch-fuses', for which 3A fuses may well not be available). If they intend that their instructions be 'more generic' and 'less country-specific', how is a user outside of the UK meant to implement this requirement for an external 3A fuse, I wonder?

Kind Regards, John

 

[winston1]

I'm not so sure about "less country-specific localisation".

A problem with boilers (and a good few other things) is the requirement in MIs for ...

View attachment 273589

(from the Worcester MI posted by eric, but very common).

My understanding is that not only do very few countries outside of the UK have fused plugs, but nor do they really have any equivalent of an FCU (other than large 'switch-fuses', for which 3A fuses may well not be available). If they intend that their instructions be 'more generic' and 'less country-specific', how is a user outside of the UK meant to implement this requirement for an external 3A fuse, I wonder?

Kind Regards, John

Once again clearly a situation where the MIs are wrong. Just about all boilers are internally fused at less than 3 amps and any external fuse is only to protect the connecting cable. Are they seriously suggesting that we we use such thin connecting cable.

 

[securespark]

I'm sure we have been here before.

There is (or at least, used to be) a requirement for all circuitry connected to a gas-fed appliance to be fused at a maximum of 3A. Boilers, water heaters, cookers, ovens, hobs.

 

[EFLImpudence]

If they intend that their instructions be 'more generic' and 'less country-specific',

They clearly do not and cannot be.

Anyway, I am sure a lot of "Manufacturer's Instructions" are merely things that the "manufacturer" thinks are required by the electrical regulations in the UK - bearing in mind that the UK is likely the exception and odd one out as far as the manufacturer is concerned.

how is a user outside of the UK meant to implement this requirement for an external 3A fuse, I wonder?

They are not. They will not be told to.

 

[securespark]

Hang on. I found this I wrote in 2018.

I have just been on the phone to the technical helplines at Worcester Bosch and Gas Safe.

WB say as far as they are aware, there is nothing in the regulations (gas or electricity) that requires a limit on fusing to 3A.
They say the boilers they manufacture for markets outside the UK are not the same as those for this market.

Gas Safe say there is nothing in the gas regulations about fuse size. But they did say that it is written into the gas regs that manufacturer's instructions MUST be followed.

 

[denso13]

But they did say that it is written into the gas regs that manufacturer's instructions MUST be followed.

No, not "must", but should take due regard of them.

 

[EFLImpudence]

There is (or at least, used to be) a requirement for all circuitry connected to a gas-fed appliance to be fused at a maximum of 3A. Boilers, water heaters, cookers, ovens, hobs.

Then surely it is up to the manufacturer to fit one.

 

[JohnW2]

They clearly do not and cannot be.

Quite - that's why I was questioning/challenging Simon's suggestion that they were!

Anyway, I am sure a lot of "Manufacturer's Instructions" are merely things that the "manufacturer" thinks are required by the electrical regulations in the UK - bearing in mind that the UK is likely the exception and odd one out as far as the manufacturer is concerned.

That's very probably true.

They are not. They will not be told to.

Quite so. Again, that's why I was 'questioning' (really 'disputing'!) Simon's suggestion that the instructions were 'generic'/multi-national, since they would clearly only be applicable in the UK!

Kind Regards, John