"dennis@home" wrote in message
...
On 23/10/2019 21:31, wrote:
On Wednesday, 23 October 2019 18:15:26 UTC+1, 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).

Cheers, T i m

There are 2 types, motorised & solenoid. The latter are cheaper & noisy.
AFAIK both use spring return.

A third type has motorised open and return but the wiring is slightly more
and they cost more.
They are quiet.

I think mine is the third type. It has a little slide lever on the housing
which is spring-loaded. If you move it you can feel that it is making a
shaft spin at high speed. There is no indication as to whether it is opening
or closing the valve, and it seems to take about two movements of the lever
to go from fully closed to fully open and then another two to go back to
fully closed. It would have been so much more useful if the motorised
housing had had an indicator that changed between "closed" and "open". I
presume the valve is rotated by the motor in one direction only and can go
from "open" at 0 degrees and 180 degrees, and "closed" at 90 and 270
degrees.

In order to heat the part of my house that was controlled by that valve, I
had to manually move it to the "open" position (as determined by feeling the
downstream pipes when the boiler and pump were running. I then had CH which
was controlled by the thermostat of the other CH zone or by the HW
thermostat - so if *either* was on, the zone with the dead valve got hot.
Rather than keep wriggling through the absurdly small "fairy door" that
gives access to that part of the loft, we used the individual radiator
valves to regulate the heating until the CH engineer could come out to
replace the valve.

One interesting thing. I gather that these valves are turned on by the
programmer and thermostat in series both being turned on. This moves the
valve to the "open" position which also turns on the power to the boiler and
pump via a logical OR arrangement: if any of the Zone 1 CH, Zone 2 CH or HW
valves is open, boiler and pump are turned on; boiler and pump are turned
off only when all three valves are closed. However although the dead valve
was getting power, it was not sending a permanent enable signal to the
boiler and pump even though it was in the "open" position. So not only had
the motor stopped working but also the boiler-enable wire was also not
working. That was a good thing, because it would have mean that the boiler
was running all the time that the programmer was "on", irrespective of the
Zone 2 and HW thermostats. (*)

Thankfully normal service has been resumed and the two zones are each once
again controlled by their own programmer and thermostat.


(*) I noticed that the electricity consumption (which I read every few days
while we are getting used to the vagaries of our new house) was excessive.
I'd thought it was due to the CH motor running all day long (apart from
overnight), until my wife said "damn, I forgot to turn off the underfloor
heating in the kitchen" (I remember her switching it on). I think *that* was
the cause of the excessive electricity usage - everything is back to normal
now we've switched it off. Memo: change the master switch for the underfloor
heating either to one with a light which is on all the time the heating is
switched on (independent of the one that lights only when its thermostat
calls for heat), or else to a programmable timer which only allows the
heating to be turned on for a few hours before resetting to the "off" state.