Drayton valve 'sticking'

[Gary C]

Paul Drawmer said:

Gary C said:

Just replaced the microswitch in our ZA6.

They get sticky but are an off the shelf part if your that way inclined. At £3, a lot cheaper than a £70 new head. Fairly simple solder job but make sure you dont loose the springs. Also these bodies age, the plastic cracks and the springs detach, you can hook them back through the holes in the body where the hooks for the springs sit.

https://uk.rs-online.com/web/p/micro-switches/1616...

Edited by Gary C on Saturday 19th November 10:11

That's interesting, thank you.

No problem

They are a bit of a bugger to put together and get all the springs in place (and as a former instrument mechanic it was the sort of thing I did my apprenticeship in) but if your fairly handy, its dooable, just make sure the powers off

[Paul Drawmer]

Lincsls1 said:

So it seems you have mistakenly diagnosed the wrong head as the one keeping the system running.
Either get another new actuator and replace the other one, or if you've got the old one, put that on.
What the boiler out of interest?

I got it right last time, but need diagnostic help this time. How do I tell which of the two valves in the airing cupboard is at fault? Last time, a sharp tap on the errant valve cover would make it switch. This time that doesn't work. I've tried manually activating the valves but that's not making it switch off.

So, is the only way to get into the rats nest and sort out which is live when it shouldn't be?

[Lincsls1]

Gary C said:

Note, its been 7 years since he replaced the head, so I think its safe to assume he got the right one, just that its failed again.

Ah yes!

[CorradoTDI]

Paul Drawmer said:

I'm stiffer now than I was at 69!

They are under £50 now btw...

https://www.screwfix.com/p/drayton-27100sx-2-port-...

[Lincsls1]

Paul Drawmer said:

I got it right last time, but need diagnostic help this time. How do I tell which of the two valves in the airing cupboard is at fault? Last time, a sharp tap on the errant valve cover would make it switch. This time that doesn't work. I've tried manually activating the valves but that's not making it switch off.

So, is the only way to get into the rats nest and sort out which is live when it shouldn't be?

Sorry fella. I was totally oblivious to the fact that the first fault was 7 years ago!
First off, just make sure that the actual valve bodies are not stiff or seized open. This would stop the actuator/s from closing and breaking the circuit. If the heating valve was then obviously you'd know because the radiators will be warm all the time.
The hot water valve would be less obvious if you're used to having loads of hot water all the time.
Assuming the valves aren't seized open, then yes the correct way would be to turn the power off, remove both the grey and orange from an actuator and test its continuity with a meter. Short circuit would mean switch involuntary closed and that would be the culprit.