On 23/10/2019 18:48, charles wrote:
In article ,
T i m wrote:
On Wed, 23 Oct 2019 16:30:30 +0100, charles
wrote:

snip

You can buy two port valves with switches to turn them off at end of
travel but they cost more than the stall motor, spring return valves.

Trouble with spring return vales is they are noisy when they close..

I'm not sure if there any that work like a solenoid but the return
spring jobby I have in my hand right now is near silent in operation
(both ways).

We had one which suddenly started clanging very loudly; SWMBO got someone
in while I was away - could't find a fault, I replaced the valve and it was
better. This summer I fitted a motor open/motor shut, did a bit of
rewiringb and it's now all quiet.

Odd. When power is removed, it usually takes a couple of seconds for the
valves to close. The spring pulls on the mechanism, but the mechanism
has to drive the unpowered motor round. The high gear ratio means that
there is a lot of drag. The slow closing means that they are normally
quiet (a slight whirr and a virtually inaudible bump). We have 9 of
them, mostly over 16 years old, and none make a noise.

SteveW