Electrics provision for system boiler and megaflow with immersion heater

[EFLImpudence]

It is quite sensible if they do. Plugs do have a separation of >3mm.

It should be fitted with a 3A fuse, though.

 

[ban-all-sheds]

A plug & socket is a suitable device.

I think TTCs question was which makers say they are preferred over an FCU.

Why do you think it is quite sensible to prefer them?

 

[EFLImpudence]

I realise TTC was just asking and I was just saying that, if any MIs do state that, it is quite sensible.

Why do you think it is quite sensible to prefer them?

A bit of a play on words there.

I didn't say it was quite sensible to prefer.
I just said it is (would be) a quite sensible instruction - meaning not an insensible one.

However, better for plumbers ?

 

[ban-all-sheds]

A bit of a play on words there.

I didn't say it was quite sensible to prefer.

I think you did.

Some boiler MIs state an unswitched 13A socket rather than an FCU as the preferred connection method.

It is quite sensible if they do.

I just said it is (would be) a quite sensible instruction - meaning not an insensible one.

I think you'll find that in common parlance, to describe something as "sensible" is giving it a positive attribute, not merely stating that it is not senseless.

However, better for plumbers ?

I'm sure they are just as capable of messing up the installation of a plug as they are an FCU.

 

[EFLImpudence]

Ok, fair enough about preferred.

I think you'll find that in common parlance, to describe something as "sensible" is giving it a positive attribute, not merely stating that it is not senseless.

Mmmm.

Do you not think a plug is a sensible way to supply or isolate a boiler?

 

[Taylortwocities]

Using a plug is a way of doing it. And BS7671 lists a plug and socket as a valid method of isolation.
Usually plugs are used for portable, or at least moveable, equipment.
Boilers tend to be fixed to the wall and stay there for decades, and an FCU is more appropriate in those cases. It also stops the cleaners from unplugging the boiler to get power to the vacuum cleaner.
I only queried this as wundaboy stated

Some boiler MIs state an unswitched 13A socket rather than an FCU as the preferred connection method.

and I want to see which boiler manufacturer requires this unusual stipulation.

Hey, wundaboy, got any links/evidence/etc??

 

[wundaboy]

Sorry for late reply, been a long day.

Vaillant is the one I've come across - e.g. page 9 in this link (15Mb download)

'Isolation is preferably by the use of a fused three pin plug and unswitched shuttered socket outlet, both complying with the requirements of BS 1363. Alternatively, a 3 Amp. fused double pole switch with a 3 mm contact opening on both poles may be used.'

 

[ban-all-sheds]

Do you not think a plug is a sensible way to supply or isolate a boiler?

No, I don't think it is not sensible.

But that is irrelevant, and not what I was talking about.

 

[ban-all-sheds]

'Isolation is preferably by the use of a fused three pin plug and unswitched shuttered socket outlet, both complying with the requirements of BS 1363.

It's quite possible that that is another example of why plumbers should not be allowed near electrics.

 

[wundaboy]

Plumbers regularly ask me to provide an unswitched single socket for a boiler supply and, around here at least, you see it very frequently for boiler installs old and new. To me, it's obviously a convention that has been around for a long time.

Personally, I don't have any preference - as long as DP isolation is achieved that's all my concern is. Just thought I'd mention it

 

[Taylortwocities]

Ah. A plumbers' convention.
A bit like their useless requirement to bond all pipes going to a boiler, perhaps.

 

[Jupiter01]

Hi All,

Can I please tap into your knowledge banks again.
If one has a 35 KW System Boiler and a 300 Litre Megaflow cylinder (I'm hoping this indicates the Immersion Heater that will be required as part of this), is 2.5mm twin and earth in the way we have discussed sufficient?

I ask since I am getting dfferening opinions from builders and plumbers. Some are suggesting that 2.5mm is adequate whereas some suggest that a thicker cable is required.

Thanks in advance.

 

[EFLImpudence]

You seem to have been given all the information already but seem unable to grasp it.

Shouldn't these systems be installed by specially qualified heating engineers?

 

[Taylortwocities]

If one has a 35 KW System Boiler

This system boiler. What is the fuel? oil, gas, electricity?

 

[flameport]

is 2.5mm twin and earth in the way we have discussed sufficient?

The immersion heater is 3kW, or about 13 amps.
2.5mm T&E is rated to about 26 amps, less if through insulation or some other materials, but in any event far more than the 13A for the immersion.
The immersion is there to heat the cylinder in case the boiler breaks. It will probably never be used.

Assuming this is a gas or oil boiler, it requires next to no electrical power, hence the 3 amp fuse.
The boiler output and cylinder size have no relevance to the electrical supply.

If one has a 35 KW System Boiler

then either you have a very large house to put it in, or it's grossly oversized.