Does boiler need FCU in same room?...

[OscarLomax]

Hi all, wanted to check my electrician's heating scheme with the experts...

Our boiler is in bathroom and controls/wiring centre thing is downstairs in kitchen. The fused switch for boiler and controls is in kitchen in nice accessible place... but obviously nowhere near the boiler. Is that ok? A single cable comes up from the wiring centre to both power the boiler and switch it on. Didn't know if there was a requirement to have local isolation right at boiler?

Thanks in advance for your comments

 

[stem]

If you have the type of system where the electrical parts (pump, boiler, programmer, wiring centre, motorised valve(s)) are spread around your home, the FCU will isolate them all, and cannot be located next to every part. However wherever it is located, it should be easy to identify it and what it does. There are also rules about where they can and cannot be located in bathrooms.

In recent years, it has become common to install a separate isolator next to the boiler, so that when it is being serviced, it can't be powered up from elsewhere. But that would be its only use. Many boilers don't take kindly to having their power switched off and it may raise an alarm / fault that needs a reset. Boilers usually have a shut down sequence to follow and should be turned off using the on / off switch on the boiler itself which will allow the sequence to run its course.

 

[OscarLomax]

Thanks stem, I have got a labelled FCU so am happy that it's clear what it does. Just seemed strange not to have an isolator right by boiler. Spark pointed out that if you did have one it would have to isolate the 'heating call' signal too otherwise the boiler would be unpowered but still live, but he didn't seem to know whether one was required when I quizzed him.

 

[bernardgreen]

• Having a means to ensure the boiler is and remains isolated when it is being serviced is sensible. If someone accidently turns ON the SFCU in the kitchen while the boiler is being serviced then the service technician could be electrocuted or otherwise injured.

 

[stem]

Spark pointed out that if you did have one it would have to isolate the 'heating call' signal too otherwise the boiler would be unpowered but still live

That is correct, but 3 pole isolators, the type used for extractor fans with a switched live supply are readily available and can be used to provide local boiler isolation.

However, I think the majority of installations will still be like yours.

 

[OwainDIYer]

• Having a means to ensure the boiler is and remains isolated when it is being serviced is sensible. If someone accidently turns ON the SFCU in the kitchen while the boiler is being serviced then the service technician could be electrocuted or otherwise injured.

the service technician should lock out the FCU before exposing live parts inside the boiler, but it will often be necessary to have the boiler energised during servicing for combustion analysis to be taken.

 

[Taylortwocities]

You should add a sticker on the boiler to say where the isolation switch is. You may not be there when the emergency plumber comes to call.

 

[ban-all-sheds]

Boilers usually have a shut down sequence to follow and should be turned off using the on / off switch on the boiler itself which will allow the sequence to run its course.

After which it can be isolated.

(Assuming that there is no fault in its control gubbins stopping it from shutting down properly )

 

[OscarLomax]

Thanks all, think I'll get him to put a 3-pole isolator in boiler cupboard, that way the gas bloke might survive my Mrs turning the heating on during its annual service.

...and I'll label boiler to state where FCU is.

 

[ban-all-sheds]

Sounds good.

Make sure he doesn't take the earth connection through the switch.

 

[EFLImpudence]

Why do you need a three pole isolator?

If the FCU switches off all power to the heating system - as it should - then the call for heat will be dead as well and/or the boiler will not work.

If not it is not wired correctly.

 

[PrenticeBoyofDerry]

but it will often be necessary to have the boiler energised during servicing for combustion analysis to be taken.

Which would be done with the boiler cover on, so there would be no danger of being exposed to live electrical parts within the boiler.