just studying s plan wiring diagrams...

[Howsie]

With an S plan just remember you have 2 channels of switched wires in series: one HW & one CH. As said all neutrals & earth wires are common. The only other thing is a perminant live switched by the zone valve micro switch pulling on the boiler.
A very simple 'on/off' control system.

The clue is in Dickie's first sentence and he is right.

 

[Dickie]

If they were wired in series like the lightbulbs in your picture then all three would need ti be energized to make a one zone circuit.

Parallel diagram shows how three valves create three zones

It's two channels, one for the HW & one for the CH; the room thermostat is 'made' for the CH zone valve to open & the cylinder thermostat is 'made' for the HW zone valve to open - a simple 'on/off' in series circuit.

 

[kay-jay]

I get that.
The two functions are series. I missed the bit about the s-plan.
I thought we were talking about circuits rather than wiring

 

[Ermintrude]

With an S plan just remember you have 2 channels of switched wires in series: one HW & one CH. As said all neutrals & earth wires are common. The only other thing is a perminant live switched by the zone valve micro switch pulling on the boiler.
A very simple 'on/off' control system.

Two channels in series means only works when both were on. Two channels, wired in parallel but each with series controls . Was trying to help the op understand.

 

[Howsie]

You can't have two channels in series; that's one channel.

 

[Ermintrude]

You can't have two channels in series; that's one channel.

You previously said that having two channels in series was correct?

 

[Howsie]

I did and it is.

 

[doitmyself]

With an S plan just remember you have 2 channels of switched wires in series: one HW & one CH.

When I first read that it appeared to say that the HW channel is in series with the the CH channel, which is WRONG. But then I saw the "switched wires in series" bit and wondered if Dickie was referring to the HW thermostat being in series with the HW timer (and similar for the CH channel), which is correct.

So I asked the question, which started a long discussion. Just shows what can happen if someone doesn't make himself clearly understood.:wink5:

 

[mutley racers]

Wow, now that was an interesting read. So basically all controls in hot water side are in series, which means they all turn on and off at the same time like Christmas tree lights. And the same for ch

 

[Dickie]

No, the programmer don't control the Xmas lights. Well, unless you want it to??!!

 

[mountainman]

Wow, now that was an interesting read. So basically all controls in hot water side are in series, which means they all turn on and off at the same time like Christmas tree lights. And the same for ch

All controls are in series for their respective zones be it multiple HW cylinders, heating zones and UFH.
Keep this fixed in your understanding and 'S' plan is simples.