Do zone valves get “tired”?

[alan_m]

In 30 years on my CH system I've only had to replace one 3 port valve.

[Davey]

The only one I have is a 2-port unit. I think I should be glad.

[Harry Bloomfield Esq]

The MOMO design of 3-port seem, by design, to be more reliable - no springs involved, no deliberate stalling of the motor under power. They just motor to position, then switch completely off, until called to move again.

[charles]

There are two port valves like that, too. They are making comeback.

[The Natural Philosopher]

A lot depends on how much limescale build up you get. A good installation with no leaks and full of additive in a soft water area is fine. But when you are in a hard water area and a lot of topping up without additives goes on - typically because of a failed pressure vessel or minor weeping from some gland - you get scale build up the jams the valves.

[ponyface]

what if you operate the remainer ?

[alan_m]

I expect systems to fail more with a lack of maintenance and running without an inhibitor.