The hot water and central heating is timed to go on in the afternoon 4pm to 1030pm every day and has been working fine for the last 7 years, I think the whole system is around 11 years old.
One evening I found that the temperature of the water coming out of the upstairs shower was warm and I couldn't get it to go hot, no matter how much I adjusted the shower control
I then checked the temperature of the pipe coming out of each ZA5 valve, heating pipework was hot entering the valve and leaving the valve.
Hot water pipe was hot going into the ZA5 valve but only a little warm going out, towards the hot water cylinder.
I turned off heating and hot water via the timer and could move the slider switch on both ZA5 valves and they would then return fine by themselves.
I snapped off the electric head of each and couldn't see anything (although I understand I probably wouldn't see anything unless they were dismantled) and
snapped them back on.
Now I seem to find that there is hot water in the evening. I'm assuming that having moved the sliders on each ZA5 valve has maybe freed the hot water ZA5, sticking maybe? but now there does not seem to be any hot water in the morning, whereas their used to be hot water all day long (left over from the night time).
I'm just wondering if I changed the snap on ZA5 zone valve (actuators) would help and is it worth changing the whole valve including the compression pipework ?
I have not changed any hot water temp on the hot water cylinder thermostat.
Is it ok to just change the snap on ZA5 actuator part on the zone valves (£52) and not having to drain the system,
or for the sake of £12 extra is it better to change the complete value with pipework attached but would mean I have to drain the system down first ?
Any help or suggestions as to trying to diagnose what is causing the problem and ZA5 actuator or whole unit replacement would be much appreciated.
There is an A and B labelled slide of some kind on the side of the ZA5 that does not seem to move, not sure if that is important.
I'm going to keep running the heating / hot water as normal over the few days to see exactly what is happening.
Apologies for the length of this post.