Central Heating & Hot Water wiring

[EFLImpudence]

I need one switched live from the programmer in the cellar to the cylinder stat in the attic;

I realise the tank and boiler are close but...

and another from the prog to the room stat in the hall. Is it okay to use twin & earth leaving the neutral unconnected?

How will the valve know when the thermostat is calling for heat.

You're not doing it correctly - talking about single wires - running here to there.

As has been said in various posts -
You need to plan it properly and run cables with the necessary number of cores from each appliance and accessory to, normally, one central point.
As your system is so spread out you may need two, I suppose.

You do not use single wires from programmer to thermostat to valve to boiler.

 

[bernardgreen]

If you are having only one isolation point then consider making it impossible for someone else to accidently switch it back on if you are working on the system at one of the other areas. Removing the fuse is one way to reduce the risk to near zero.

 

[orval]

If you fancy a laugh, take a look at my really badly drawn diagram:

Untitled

• orval
• 21 Nov 2011
• 1

The rectangles with all the little circles are supposed to be wiring centres. I'll be using connector strip inside Ashley & Rock J701 boxes.

The ovals around the wires represent a cable. So as you can see there's quite a lot of 6243Y.

The last thing I'm a little unsure of is the 6242Y carrying the programmer output from the cellar wiring centre to the attic wiring centre. Obviously I would use red sleeving/tape to indicate that the blue is a switched-live. But is there a preferred way of doing this?

 

[holmslaw]

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[orval]

You've missed out the earth wire on the 2 core ch and hw switchlines from the programmer, should be a twin and earth..

Of course. I had it in mind, just missed it off the diagram!

The cylinder stat, a neutral is sometimes required, so the cable should be a 3c and earth.

I'm not sure what model of cylinder stat I have. I'll check. I took many hints from a circuit diagram on the zone valve installation instructions, hence no neutral connection:
www.honeywelluk.com/Documents/Full-Install/pdf/1081.pdf

Otherwise looks ok, and I think you now appreciate the impracticalities of additional isolation points. However, bernard green made a good suggestion of installing additional isolation points on the main feed. They would go in the live wire between the 3A fsu (sic) and the boiler. You could also fit neon locaters that illuminate when the isolation points are switched off, they would serve as a reminder that although the system is dead the isolation switch is still live.

Thanks. I definitely realised how much of a pain three isolators would be! BTW by FSU I mean Fused Switch Unit. I think what I actually mean't was FCU.

I've just realised I may have bought the wrong thing for isolation: it's a "13 Amp Unswitched Fused Spur with + Neon". Obviously I was going to put a 3A fuse in it, but perhaps I need a switched version?

 

[holmslaw]

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[orval]

Thinking on I would defintely go with the extending the main isolation point. It will make repairs, commisioning, fault finding so much easier. I have added them to your diagram.

Hmm, I'm probably being a right dimlo but I can't find any SP switches with neon.

So you recommend a neon switch and a neon locator? How would that be wired?

I take it I'd used twin & earth for the these, connecting the earth to the back boxes?

 

[ban-all-sheds]

Hmm, I'm probably being a right dimlo but I can't find any SP switches with neon.

You won't - they'd never work, would they....

 

[matt1e]

The cylinder stat, a neutral is sometimes required, so the cable should be a 3c and earth.

Hi holmslaw
you're getting mixed up between room stats (where sometimes a neutral is req) and cyl stats (where sometimes a 3 core and earth is req but it is not a neutral it is a switched live from the the satisfied terminal (for wiring 3port valves)

Matt

 

[holmslaw]

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[holmslaw]

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[EFLImpudence]

If you're going to have the three isolators why not supply the system at the bottom connectors?

 

[holmslaw]

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[EFLImpudence]

In your amended diagram - instead of taking a cable back to the top, feed L & N plus the cpc to the lower connector block.

 

[holmslaw]

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