Central Heating Wiring

[cjgarlick]

Morning all -

Can anyone please confirm the type/spec of cable required to wire up a central heating system, eg) between C/H Programmer and ancillaries like Zone Valves, Cylinder Stats, Room Stats etc ?

Thanks in advance -

 

[alexnic]

1.0mm twin & Earth is sufficient ...

 

[breezer]

if your central heating is run from a spur ( it can also be from a plug) it should work with a 5 amp fuse, this would then mean you can use flex of a greater rating, however for longer runs i.e. thermostat do use 1.00 mm twin and earth. also always connect the earth wires.

 

[cjgarlick]

Thanks to you both for replies so far.

If it's usual to use T+E then that's what I'll do. I was really wondering about (eg) wiring to the Zone Valve, which has five differently coloured wires. I wondered if there was a 'special' type of cable (ie - five cored) for wiring that up, instead of using two runs of T+E (ie - four cores and an earth). Just seems to me that this could get a little confusing at the wiring junction box.

Does this make sense? Any further coments gratefully received.

Thanks again -

 

[breezer]

do not quote me on this, but i do not think it uses all 5 wires,( I could be wrong) what do the valve instructions say, I would be curios to know

 

[cjgarlick]

I'll let you know what the instructions say when it arrives from Screwfix tomorrow !!

I'm looking at a typical wiring layout, which suggests a 3-port valve has an earth, a neutral, a live feed from a cylinder stat, another from a room stat, and a link back to the main Programmer. It's a PDF though so I can't figure out how to in-line it for you in this post (ie - can't just put a link to it as per normal). I downloaded it from Horstmann's website I think, although I can't find the link again now.

Thanks for your help.

 

[breezer]

thanks for that, if you check under your browsers "history" icon you should find the link there.

I did not know it required that many wires.

 

[cjgarlick]

Hi Breezer - here's the URL for that wiring diagram I was referring to:-

http://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/Pics.pdf

I'm looking at the Honeywell 'Y Plan' layout, using a Horstmann C27 controller.

Are you 100% that T+E is the standard cable to use for this? Looking at (eg) the room stat, or the cyl. stat, they both need 3 connections but have no earth... meaning a double run of T+E for each of them (ie, 4 usable cores). Just seems a bit messy to me ...?

Cheers

 

[alexnic]

Re:the thermostat / cylinder stat req. 3-cores (no earth), your quite correct. sometimes they need a nuetral / live / switchwire depending on the type or make, in this case you could use 1.0mm 3-core & earth cable.

Depending on the type of central heating you have your best bet is to run the 3-core & earth from the programmer unit upto a 'C/H wiring centre' this is just a 4" x 4" plastic junction box with a terminal strip inside and preferably mounted beside the pump and diverter valves, the flexes from these will then be terminated inside the box. Also run the 2 x 3-core & earth from here to your 'stats' and these can be connected to the 'stat' flexes at source via small junction boxes. This will centralise all your connections so it should be readily accessable.

Re: supplying your boiler from a plug & socket ... this now goes against the new regulations and it must be supplied from a 3A fused spur unit otherwise BG will not entertain it!

hope this helps..

 

[cjgarlick]

>> hope this helps..

Certainly does, thanks for that.