Electricity supply for boilers

[Matt in Weymouth]

Hi,

I am looking at fitting (or having fitted) a new combi boiler. The new boi= ler would be installed into an airing cupboard in the bathroom (with suitab= le access space), to replace the existing floorstanding Thorn system boiler= in the kitchen.

In terms of electrics - if it fine for the boiler to be powered from an exi= sting ring main (fused spur, switch-able outside of the bathroom), or does = it need its own fuse direct from the CU? I am just trying to work out how = much other work would be involved.

Thanks, Matt

[Doctor Drivel]

A switched spur off the ring and inside the cupboard is fine. It is for isolation. It does not need to be switched outside the cupboard. The best is obviously a separate circuit for the boiler back to the CU with its own RCBO at the CU, and a local combi isolation switch (need not be fused as the RCBO rated properly gives the protection). Then if other circuits fail it does not make the house cold.

[Matt in Weymouth]

Thanks for your speedy response.

It is easier for me to place the switch outside of the bathroom, as that is= where I could created the fused spur into an existing ring (2nd floor ring= , which is very lightly loaded), so I might take that approach to start wit= h. Later, when I next have to crawl around in the loft space I can run in = additional cable back to the CU and have a separate RCBO.

Cheers, Matt

[ARW]

What's up Drivel? I agree with everything you have said in this post.

And if the OP has an existing immersion heater in the airing cupboard then he already has a supply direct to the CU

[Doctor Drivel]

Hava junction box ouside and spur wire tonteh combi and the Fused spur switch at the combi.

Yes, a sparate circuit for the combi is the ultimate solution. Same for the smoke alarm and freezer.

[Andy Burns]

It's the natural result of dribble arguing with dennis in various threads, two wrongs /can/ make a right ...

[Doctor Drivel]

This means you are learning. Great progress. Keep it up. Fantastic.

This immersion cable can be ulilized, as it goes back to the CU, and I have done that in the past. If he cable is there use it and just fit a fused spur in the cupboard for the combi and 6A RCBO in the CU. Sorted.

[Doctor Drivel]

Dennis? Wow! Maxie's mate.

[Graham.]

Isn't it something to do with infinite typewriters and monkeys?

[Andy Burns]

OK, so it was probably harry.

[Doctor Drivel]

What make is your typewriter?

[Doctor Drivel]

Is there any difference between those two and the Senile Jocko?

[Dave Plowman (News)]

Yup - I'm so surprised I almost bought a round.

[Doctor Drivel]

This is amazing. He must telling porkie. Senile Jockos do not buy rounds.

[Roger Mills]

Not necessarily! Mine is spurred off a ring main - and, no, I didn't do it - it's how the house was wired when built in the 1960's.

Since the immersion heater is only used in an emergency (water normally heated by the gas CH boiler) I've never bothered to do anything about it.

[ARW]

Maybe I should have said "correctly wired immersion heater" :-)

[ARW]

See the word "almost" in his reply?

[Doctor Drivel]

A 3kW immersion draws the same amps as an electric kettle.

[Doctor Drivel]

A 3kW immersion off a ring IS correctly wired. Taking the immersion on a separate line to the CU is dividing a ruling. If an immersion on a ring draws 12A and an electric kettle draw the same and the fridge/freezer kicks in and then the tumble dryer. the amps the immersion draw may be enough to trip the mcb - too much on one ring. But if the immersion is on a ring that does the bedrooms and living room only, them there it little chance of the mcb tripping as there are no other heavy appliances on the ring - I have seen 8 to 10 year old new houses wired this way.

But a separate immersion line is best and sensible.

[ARW]

For a longer time. There is a difference between the two.