On 12 Mar, 15:33, "Roger Mills" wrote:
In an earlier contribution to this discussion,

jives11 wrote:
Examining the inside of my airing cupboard with a torch I can see 2 2-
Port ACL lifestyle valves. One is definitely on the Tank coil pipe and
the other appears to be on the main CH circuit which the coil circuit
joins further up , if that makes sense. I'd guess that 2 * 2-way
switches can implement a 3 way mode where tank is open and HW is open
too.

Yes indeed. That is an S-Plan system which enables you to have just HW, just
CH or both at the same time.

This thread has been very useful. I have been tending to leave the CH
permanently on 365 days and regulate the house with the timer stat.
While this is fine in winter /cold weather , this may mean that during
Warm weather I'm probably briefly heating the house to create hot
water, as the CH will be still on as will the HW, for a couple of
hours a day at least.

If it's wired correctly, the radiators won't get hot when you're just
heating the HW (like in the summer) because the CH valve won't open unless
the programmer and room stat tell it to.

With an S-Plan system, the HW valve is controlled by the programmer and
cylinder stat, and the CH valve by the programmer and room stat. Secondary
contacts in the valve actuators close when a valve is fully open - switching
on the boiler and pump. So the boiler and pump only run when either or both
valves are open.
--
Cheers,
Roger
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Thanks Roger, I hope it is wired as you describe as that would seem
the ultimate, and would suit my preferred current method of permanent
CH regulated by a CM67 programmable stat. HW is controlled in the
'normal' way i.e 2 shorts bursts - one before I get up and one in the
late afternoon.

The only unusual aspect is that I have 4 bathroom towel rails in line
with the HW , and a landing radiator which has no shut off valves so I
ssume is always in circuit in case of a "China Syndrome" type
malfunction. A couple of the rails are shut off

I can't say if the whole thing is balanced or not but I guess that is
a whole new area to discover