wrote in message ...
On 7 May,
"spamlet" wrote:

[snip tale of 3 port valves]
As for a permanent solution: fraid I don't know.
Anyone know of any valve actuators that work a completely different and
reliable way?
At a sensible price?

I used to use 3 port valves. After numerous failures of micro switches I
modified the system to S plan+ using 2 port valves. Problem solved.

Apart from possible heating from the resistor, and hunting, I can't think
why
the 3 port valves are so much less reliable.


Sorry to hear of the numerous failures Brian (but not at all surprised!).
Possibly the difference in reliability may be due to that 'bounce tendency'
as I suspected (your 'hunting' I presume), which occurs at the middle
position, that is done away with in the two port valves.

Shame to have had to redo the whole system to get around the problem though.
We have a plumber coming to install an extra loo and shower - which means
yet more pipes in the cupboard - so this might be a point for us to look at
modifying the current layout too.

Cheers.

S