The Honeywell Motorised valve controlling the CH is sticking in the Open
position so the heating is running continuously.
In this condition there is no resistance when moving the manual lever on
the head.

If I thump it a couple of times the valve moves and closes and switches
off the boiler/pump. If I then try to move the manual lever resistance
comes in when about half way across.

When hall thermostat switches on again the valve will work correctly and
may switch off and on a couple of times but then sticks open again.

So am I going to have yet another lesson in Sods Law or will I be lucky
and find its only the motorised head that needs replacing?
--
bert

On 04/01/2021 20:30, bert wrote:
The Honeywell Motorised valve controlling the CH is sticking in the Open
position so the heating is running continuously.
In this condition there is no resistance when moving the manual lever on
the head.

If I thump it a couple of times the valve moves and closes and switches
off the boiler/pump. If I then try to move the manual lever resistance
comes in when about half way across.

When hall thermostat switches on again the valve will work correctly and
may switch off and on a couple of times but then sticks open again.

So am I going to have yet another lesson in Sods Law or will I be lucky
and find its only the motorised head that needs replacing?
In general especially if there is hard water and not enough inhibitor
these valves get sticky. You can remove the head and access the valve
spindle and see if it turns smoothly and with little effort, without
having to dismember the plumbing. Sometimes working it a few times
manually clears a bit of blockage. Other times its is simply all gunged
up and its a whole new valve.



--
€œIt is not the truth of Marxism that explains the willingness of
intellectuals to believe it, but the power that it confers on
intellectuals, in their attempts to control the world. And since...it is
futile to reason someone out of a thing that he was not reasoned into,
we can conclude that Marxism owes its remarkable power to survive every
criticism to the fact that it is not a truth-directed but a
power-directed system of thought.€�
Sir Roger Scruton

On Mon, 4 Jan 2021 20:30:11 +0000, bert wrote:

The Honeywell Motorised valve controlling the CH is sticking in the Open
position so the heating is running continuously.
In this condition there is no resistance when moving the manual lever on
the head.

If I thump it a couple of times the valve moves and closes and switches
off the boiler/pump. If I then try to move the manual lever resistance
comes in when about half way across.

When hall thermostat switches on again the valve will work correctly and
may switch off and on a couple of times but then sticks open again.

So am I going to have yet another lesson in Sods Law or will I be lucky
and find its only the motorised head that needs replacing?
One of mine went like this and it was just the gear mechanism in the
head that had worn and was jamming. A replacement head fixed it, but I
waggled the spindle on the valve body a few times just to check it was
moving freely.
You can get a Honeywell compatible head for quite a lot less £££s,
I'll see if I can find a link, but someone else might know.

On Mon, 4 Jan 2021 20:30:11 +0000, bert wrote:

The Honeywell Motorised valve controlling the CH is sticking in the Open
position so the heating is running continuously.
In this condition there is no resistance when moving the manual lever on
the head.

If I thump it a couple of times the valve moves and closes and switches
off the boiler/pump. If I then try to move the manual lever resistance
comes in when about half way across.

When hall thermostat switches on again the valve will work correctly and
may switch off and on a couple of times but then sticks open again.

So am I going to have yet another lesson in Sods Law or will I be lucky
and find its only the motorised head that needs replacing?
V4043 compatible head, see here
https://www.heatingcontrolsonline.co...ell-v4043.html

bert was thinking very hard :
The Honeywell Motorised valve controlling the CH is sticking in the Open
position so the heating is running continuously.
In this condition there is no resistance when moving the manual lever on the
head.

When in that position it is normal.


If I thump it a couple of times the valve moves and closes and switches off
the boiler/pump. If I then try to move the manual lever resistance comes in
when about half way across.

Again normal.

When hall thermostat switches on again the valve will work correctly and may
switch off and on a couple of times but then sticks open again.

So am I going to have yet another lesson in Sods Law or will I be lucky and
find its only the motorised head that needs replacing?

Yes, it needs a new actuator head. Sticking is what they eventually do,
after a few years of use. The spring return type seem particularly
prone to jamming after a bit of wear. I used to keep one on, one spare
ready to fit.

You can buy a momo (motor on, motor off) type which does not use a
spring return. The spring puts the mechanism under a lot of mechanical
stress. MOMO's do a complete turn to the required valve position, in
one direction, they are electrically more complex, so more susceptible
to water leaking into them - but not a problem if the head is
uppermost.

They are a direct swap electrically, but both head and valve need to be
a match, you cannot mix and match.

The Natural Philosopher submitted this idea :
In general especially if there is hard water and not enough inhibitor these
valves get sticky. You can remove the head and access the valve spindle and
see if it turns smoothly and with little effort, without having to dismember
the plumbing. Sometimes working it a few times manually clears a bit of
blockage. Other times its is simply all gunged up and its a whole new valve.

The spring return type actuators jam, much more often than the actual
valve. Easy to check- the D spindle of the valve should be able to be
turned, almost with your finger tips if it is free. If not, work it
back and forth a few times to free it.