On Fri, 19 Sep 2003 20:15:54 +0100, Ed Sirett
wrote:

BigWallop wrote:


Q11. I've just bought replacement sychron motor, but I can tell which
position the gear quandrant should be in when I mount the motor in
position.
All I can tell is when the motor is hanging loose and I switch W+H, then
motor activates without stopping.


A synchron motor, as with any standard motor, will continue to turn when
energised until told to stop by some kind of switching system. The small
micro-switch in the motorised valve is such a system.

With the plain 2 port valve the motor simply winds the valve open and
the valve is not able to turn any further so the motor stops - crude but
generally very reliable.



On the subject of these zone or diverter valves with spring returns,
I am sure I can remember that when I installed my first system (late
seventies), the 2 port valves that I used were motorised in both
directions - i.e. no spring return.

IIRC, the motor had two windings or some means of effecting reverse
and there was a live to drive it to open and another to drive it to
close. Then the room and cylinder thermostats were change-over
switches to do this. There was an auxilliary switch as now to
provide the demand live to the boiler.

Do you remember those and when and why they changed? This seems like
a better way to do the job than a motor powered against a spring.


..andy

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