Two zone valve - volt free conrtact to fire combi?

[1974stephen]

Hello Everyone

I'm just about the embark on a major upgrade of heating pipework to allow some zoning, and wondered if I was right in thinking that if I used a two port zone valve connected as detailed below for each zone, it would work how I want, which is to fire the boiler from a volt free contact.

Green/Yellow - Earth
Blue - Neutral
Brown - S/L from stat

Orange & Grey straight onto volt free contact to fire boiler.

If I don't put a permanent 230v feed onto the grey, to switch to the orange like normal, there's no reason why this shouldn't work and save a bunch of relays and unnecessary cabling - is there?

 

[RF Lighting]

That's exactly it. Your boiler applies the voltage to the grey wire for you, and receives it back on the orange when the valve closes.

 

[1974stephen]

Thanks RF - you say when the valve closes - do you mean open?

 

[Dan Robinson]

Yes he does . He was probably meant to say "switch closes"

Sparkies eh? Bless 'em

 

[1974stephen]

Difficult for me to comment - I'm more spark than plumb!

 

[bolshy]

I'd usually wire the grey to the 230v output from boiler for external controls - where you would normally remove a link. This provides 230v back to boiler from orange when valve opens and microswitch makes to fire the boiler up. When the boiler power is switched off, it also means that you haven't got unnecessary live wires. If you use a wiring centre as a junction box it makes life easier. If you are fully zoning heating, don't forget a hydraulic bypass for pump overrun.

 

[Dan Robinson]

Bolshy, this is about volt free switching. Something I do more nowadays than traditional S-Plans.

 

[matt1e]

Bolshy, this is about volt free switching. Something I do more nowadays than traditional S-Plans.

yes as Dan says, most modern boilers use volt-free switching nowadays anyway so its the only way to do it s-plan wise (unless you want to unnecessarily add relays and complicate things)

Matt

Ps forgot to mention
To the op, that's exactly the way to do it Steve, as others have said

 

[bolshy]

The microswitch in the zone valve is volt free - the boiler provides the signal to and from the valve microswitch, whatever voltage it may be - the programmable roomstat provides the voltage to open the zone valve, who mentioned relays? The BAXI Neta Tec for instance uses 230v switching, just as an example. This enables 4 core and earth to be used from the programmable roomstat to the zone valve, and twin and earth from the zone valve to boiler. What could be simpler?

 

[matt1e]

who mentioned relays?

The Op Bolshy

Matt

 

[bolshy]

 

[Dan Robinson]

What's complicated about a 4PDT relay or two?

 

[RF Lighting]

Yes he does . He was probably meant to say "switch closes"

Oops yes I meant when the valve opens and the switch closes.

 

[Agile]

I'd usually wire the grey to the 230v output from boiler for external controls - where you would normally remove a link. This provides 230v back to boiler from orange when valve opens and microswitch makes to fire the boiler up.

Perhaps you dont encounter modern bolers with low voltage switching.

But if you write that on an open forum then you will have hundreds of DIYers following your advice and damaging their boilers!

 

[Dan Robinson]

Perhaps you dont encounter modern bolers with low voltage switching

Low voltage or Extra Low Voltage?