I appear to have an S-plan CH/HW gas system, with 2 x 2port valves.

In the last few days the hot water has stopped heating (although
immersion is fine, as is heating)

I first tried bypassing the hot water cylinder thermostat - this made
no difference.

I believe therefore that the 2port valve leading to the HW cylinder has
failed.

The valve is a ACL Lifestyle, 28mm. There is an A/B indicator, which
stays on A. There is also a manual level I can push, which causes the
indicator to move 1/2 way to B. If I do this there is a click of a
microswitch and the pump / boiler activates fine. If I let go the lever
move backs to A and afte ra while the pump/boiler will stop.

My son reckoned he saw it move 1/2 way to B and immediately back again
when HW was turned on, but I've not been able to see this myself. It's
always on A.

I am guessing therefore that the actuator motor is not operating. I've
not checked the wiring yet, but it's probably failed?

On starting to removing the cover, I was hoping the whole actuator
might unclip - but instead it seems as if only the plastic cover comes
off, with all the "business" left attached. I've not yet examined if in
fact this can be removed dry.

Does anyway know if on the ACL Lifestyle it can be removed/replaced
easily?

I'm not a plumbing fan, so given that I also am in need of a boiler
service, am considering getting BG etc to start a contract. A few years
ago I believe they charged extra if an existing fault was present. Now
all I can see in the T&Cs for cover is

--start--
Design or existing faults

The cost of repairs needed because of design faults (unless we are
responsible), or faults which existed before you entered into the
agreement and which could not be identified on initial inspection using
reasonable care and skill.
--end--

Does this mean they'll charge for faults found on initial inspection?
Or that they won't worry about it?

I would expect I'm looking at around
- £60 boiler service
- £40 new valve/actuator
- £80 labour

??
in any case, making the BG approach reasonable.

Comments?