2 Port Valve Closed Question

[Stratf01]

I have a honeywell 2 port valve to the emersion tank which is allowing water to pass through on the closed position meaning the water is boiling hot.

A previous plumber left an old port valve in cupboard which I took to bits to see how it works.

I thought the seal must have gone inside but after looking at old one it appears very little can go wrong with the rubber ball.

So could this mean my problem is more likely to do with the springs or motor not giving enough pressure to hold rubber ball against the valve ?

I know easy option is buy complete 2 port valve assembly but I'm quite interested to find out more about these sorts of things.

Any thoughts on this really appreciate

Thank you

 

[ShaunCorbs]

The ball can get hard and not seal / a wear spot and can pass best to replace the whole valve

 

[Last Plumber]

Presuming it is in the right way round, it might be worth taking it out to inspect it prior to buying another.
If you have had 2 there may be a reason they are failing.

I have in the past seen them distorted or coated and that prevents them seating correctly.

 

[John.g]

Could possibly be the actuator, when you move the manual lever you should feel a fairly stiff resistance as it moves.

 

[MikeJhn]

Could possibly be the actuator, when you move the manual lever you should feel a fairly stiff resistance as it moves.

But not if the programme is calling for water heating then the lever will be loose throughout its travel.

Also see this thread: Zone valve replacement - https://www.plumbersforums.net/threads/zone-valve-replacement.120608/