What should I replace my mid position actuator valve with?

[Dereekoo]

Have you tried switching it of and on etc with the unit actually unclipped from the valve. Cant see the valve affecting to such a degree.

 

[JoeyT]

I have, I left it removed over night and the problem didn't happen last night or this morning.

 

[ian1182]

I did just swap over the actuator on my lunch break. The new one also gets stuck in the H position, I realised it's moving all the way over to H and then the manual lever locks in this position until there's a call for hot water at which point it unlocks and goes to W or H.

I took the old one apart to see how it works, and the mechanical behaviour of the new and old are the same. Could be the contacts as you've said.

I'll leave it a couple of days to see if it fixes the issue (without replacing the valve just yet).

Do you mean "stuck in the H position" or remains in H position?. If the last request was for central heating it should stay in the "H" position even after the boiler goes off, if the next request was hot water it would then move across to "W". It should also return to "W" if the power is turned off as the spring pulls it back.

 

[JoeyT]

Thanks. That's right, it stays in the H position, but for some reason continues to keep the boiler and pump powered until it moves back to the W or M.

(I originally thought it would go back to W or M when it's not energised but understand that this is by design).

Would I be right in thinking then that it's better on the actuator to have the hot water turn off after the heating turns off, so that it de-energises and moves back over? Might make it last longer?

 

[ian1182]

I assume that the roomstat is up to temperature, the boiler & pump should stop. If the boiler remains running that's not correct.

As for the second part, that is difficult in reality. Due to the Y-PLAN design, in the HW satisfied or HW off position a voltage is maintained on the mid-port valve grey port which keeps the valve in the last used location. In the winter that's generally H. The only way it will revert to W after the central heating demand ceases is when the hot water tank thermostat is NOT satisfied which is rarely true. You can force a switch by turning up the hot water tank thermostat and once the valve moves across to W turn the stat down.

You should review the excellent JW youtube videos on how it all works

 

[Johntheo5]

Not quite that simple I think. IF You have CH & HW selected and the HW is satisfied then the valve will be in the CH position, if you then switch off the HW then the valve will still remain in the CH position, and will remain so even if the CH Is satisfied or switched off as its the HW off live via SW1 I think is keeping the valve in the CH position, the HW stat would have to call for heat before the valve will then spring return to the HW position, or something along those lines.

 

[ian1182]

Have you tried the various permuations to see if there is a pattern to when the boiler does not stop?

For example
(1) HW only - run an on / off cycle. Valve should move to W if not already there and remain at W once HW goes off
(2) CH only - likewise, Valve should move to H and remain there once CH goes off
(3) HW on, allow to run, the CH on, valves moves to "M", CH off, does valve revert back to W
(4) CH on (H), then HW on (does it move to M), HW off (does it go back to H)
etc

In all cases when neither HW or CH are required the boiler should go off. If you can narrow down when the problem occurs that should assist in diagnosing the cause.

 

[JoeyT]

So frustratingly, I can't get the problem to happen when manually testing any combination. But over time, by changing the timers to change the order of what comes on when:

1. 7am HW comes on, 8am Heating comes on, 9am both turn off = Heating often gets stuck on
2. 7am HW comes on 8am HW goes off and heating comes on, 9am heating turns off = Heating often gets stuck on
Not tried hot water to come on last, but manually turning hot water on and then off fixes it.

The indicator on the actuator moves between all 3 positions correctly.

Worth mentioning that the valve was previously stuck in the mid position (about a month ago), so when the hot water came on, the heating came on too, I freed it up with an adjustable spanner so now that problem is fixed, just the heating getting stuck on remains.

Could it be that the actuator microswitches are behaving differently once being stuck on for a while / heated up from the pipes which is causing the problem? Would explain why I don't get it when I manually try to trigger the issue which doesn't let it heat up.

 

[ian1182]

So frustratingly, I can't get the problem to happen when manually testing any combination. But over time, by changing the timers to change the order of what comes on when:

1. 7am HW comes on, 8am Heating comes on, 9am both turn off = Heating often gets stuck on
2. 7am HW comes on 8am HW goes off and heating comes on, 9am heating turns off = Heating often gets stuck on
Not tried hot water to come on last, but manually turning hot water on and then off fixes it.

The indicator on the actuator moves between all 3 positions correctly.

Worth mentioning that the valve was previously stuck in the mid position (about a month ago), so when the hot water came on, the heating came on too, I freed it up with an adjustable spanner so now that problem is fixed, just the heating getting stuck on remains.

Could it be that the actuator microswitches are behaving differently once being stuck on for a while / heated up from the pipes which is causing the problem? Would explain why I don't get it when I manually try to trigger the issue which doesn't let it heat up.

Taking your first example. Whilst the HW comes on at 7am and "off" at 9am, it may actually go off prior to that if the HW tank gets up to temp. It may well cut out before 8am. Hence it's not the nominal time on the programmer indicates but when it actually stops.

But any intermittent fault is the most difficult to identify.

 

[JoeyT]

Thanks everyone. I replaced the actuator on Wednesday and the problem didn't happen since. Today I've drained the system completely and replaced the valve anyway, new one is much easier to turn than the old one so was worth doing. Old one had alot of black stuff in it, but still a bit stiff after a quick clean.

Now sitting here staring at the valve to make sure it doesn't leak (first attempt at plumbing anything).

Thanks again.

 

[terryplumb]

Did you add inhibitor when refilling the system ?

 

[JoeyT]

Did you add inhibitor when refilling the system ?

Sentinel X100 I used. Poured into header tank as it filled.