A cautionary tale for those investigating probs with their central heating:

A couple of years ago I finally tracked down a problem that had had
generations of visiting plumbers busy, in frenzied and expensive, radiator
bleeding / pump replacing exercises, all to no effect, at a friend's house.
On careful analysis it turned out to be the motorised valve actuator
(Danfoss) that was the culprit all along.

More specifically, it was due to the pair of crap semi-micro switches inside
the actuator, which perform an elaborate 'dance' with the motor to wind the
valve back and forth between the three port positions. As with all contacts
(like the equally crap ones in mouse buttons), they need cleaning from time
to time, but as these are fixed inside the actuator assembly they are both
difficult to get at, and even more difficult to clean, or replace.

When the main one of these gets dirty and stops conducting, the valve stops
in the half-way position, and the room thermostat appears to have packed up,
as it 'ceases to turn the 'CH' off' because the water keeps circulating even
when it is apparently set at HW only. There is also less pump power to the
(wrongly shared) CH side, so people start trying to rebalance/bleed etc.
rads, and eventually start blaming the pump. The last thing anyone seems to
think of is the valve actuator for some reason (possibly because they are so
outrageously expensive!).

Back then, initially, I tried to just replace the switches, and did manage a
short term repair after replacing one of them: they are very cheap even at
Maplins. The other one soon failed, however, and the way it was mounted led
to the ancient plastic mounting plate breaking when I tried to get it off.

So had to grit teeth and face up to buying a new valve/actuator assembly:
and thought I'd better do the valve as well while I was at it (which also
means more expensive/inhibitor, anti knock down the drain: if only I'd
thought to put a stop cock on the outlet to the ch system header tank while
I was at it...)

After extensive reading of these columns and those of the Screwfix Forum -
and some very silly stick from posters who simply would not believe that a
semi-micro switch could ever fail - I decided to opt for the more expensive
Honeywell V4073A valve and actuator which cost me £60.44 on 15 Nov 2005.

Up until now this seemed to have been a good buy: it had been easy to fit;
had what seemed like a clever ball arrangement rather than flaps in the
valve itself; and a quiet and smooth switching action.

However, I recently began to notice that the CH seemed to be on when it
should not be, so had a closer look yesterday: AND Lo!, inside are just the
same crap switches as in the Danfoss! At first, all seemed not lost, as
these ones were mounted on their own little circuit board, which could be
removed for easy working. Unfortunately, the way they were arranged, they
could not be opened for cleaning until one had been removed from the board,
but once open they were easy to clean the muck off the contacts.

In the Honeywell case however, there was the additional crapness of a
largish 12k resistor which had been dry jointed and was coming in at 20k as
a result, and overheating the circuit board to boot. So I had to resolder
this along with the cleaned switch.

Then the fun really started!
How they assembled the thing I don't know, but the actuating
cams/gears/springs etc, are mounted on such a flimsy metal plate that it is
almost impossible to put the actuator back on the valve and still have
moving parts at the end - the slightest overtightening of a screw, and the
whole thing distorts and nothing moves. "Grrr" - and worse, I said many
times as I struggled in a corner of a tight cupboard with a red hot water
cylinder, for hours to get it to work 'properly'. (Yes I emptied the tank
in the end; and yes; the water in the resulting bath was cold by the time I
was ready for it!)

Once it became mobile, another problem presented itself, in that, on moving
to the centre position from either side, an oscillating motion tended to be
set up with the motor driving its cam against the switch arms/springs and
being bounced rather than operating the switch that turns it off. Click,
click, click, click etc. It may well have been this oscillation tendency
which had burned the switch contacts 'prematurely'.

With much fiddling, I managed to - temporarily I expect - bend the switch
arms enough to correct the bounce, and get it all 'working'.

BUT what a load of crap for what a load of cash!

With this experience, I can say that, if I had had the old Danfoss (really
old) heavy duty gearing, and the Honeywell circuitboard switch mounting
method, I could have at least had an assembly that was easy to get on and
off and reasonably robust; with switches that could be replaced
occasionally. But why are they allowed to get away with still using the
same 'failure guaranteed' switches whilst charging prices which ought to
come with a lifetime guarantee?!

As I would imagine that numerous CH systems must be in a similar state -
unless I have just been extremely unlucky! - with many other people throwing
away money trying to solve 'circulation/air lock/pump/thermostat' problems,
unaware of the nature of these valve actuators, I thought UK-Diy'ers might
appreciate this tip.

With any luck some people reading this might save themselves from wasting
cash test-replacing non faulty parts of their systems.

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?

Take care,

S

"dennis@home" wrote in message
...


"spamlet" wrote in message
om...
A cautionary tale for those investigating probs with their central
heating:

A couple of years ago I finally tracked down a problem that had had
generations of visiting plumbers busy, in frenzied and expensive,
radiator bleeding / pump replacing exercises, all to no effect, at a
friend's house. On careful analysis it turned out to be the motorised
valve actuator (Danfoss) that was the culprit all along.

More specifically, it was due to the pair of crap semi-micro switches
inside the actuator, which perform an elaborate 'dance' with the motor to
wind the valve back and forth between the three port positions. As with
all contacts (like the equally crap ones in mouse buttons), they need
cleaning from time to time, but as these are fixed inside the actuator
assembly they are both difficult to get at, and even more difficult to
clean, or replace.

When the main one of these gets dirty and stops conducting, the valve
stops in the half-way position, and the room thermostat appears to have
packed up, as it 'ceases to turn the 'CH' off' because the water keeps
circulating even when it is apparently set at HW only. There is also
less pump power to the (wrongly shared) CH side, so people start trying
to rebalance/bleed etc. rads, and eventually start blaming the pump. The
last thing anyone seems to think of is the valve actuator for some reason
(possibly because they are so outrageously expensive!).

Back then, initially, I tried to just replace the switches, and did
manage a short term repair after replacing one of them: they are very
cheap even at Maplins. The other one soon failed, however, and the way
it was mounted led to the ancient plastic mounting plate breaking when I
tried to get it off.

So had to grit teeth and face up to buying a new valve/actuator assembly:
and thought I'd better do the valve as well while I was at it (which
also means more expensive/inhibitor, anti knock down the drain: if only
I'd thought to put a stop cock on the outlet to the ch system header tank
while I was at it...)

After extensive reading of these columns and those of the Screwfix
Forum - and some very silly stick from posters who simply would not
believe that a semi-micro switch could ever fail - I decided to opt for
the more expensive Honeywell V4073A valve and actuator which cost me
£60.44 on 15 Nov 2005.

Up until now this seemed to have been a good buy: it had been easy to
fit; had what seemed like a clever ball arrangement rather than flaps in
the valve itself; and a quiet and smooth switching action.

However, I recently began to notice that the CH seemed to be on when it
should not be, so had a closer look yesterday: AND Lo!, inside are just
the same crap switches as in the Danfoss! At first, all seemed not lost,
as these ones were mounted on their own little circuit board, which could
be removed for easy working. Unfortunately, the way they were arranged,
they could not be opened for cleaning until one had been removed from the
board, but once open they were easy to clean the muck off the contacts.

In the Honeywell case however, there was the additional crapness of a
largish 12k resistor which had been dry jointed and was coming in at 20k
as a result, and overheating the circuit board to boot. So I had to
resolder this along with the cleaned switch.

Then the fun really started!
How they assembled the thing I don't know, but the actuating
cams/gears/springs etc, are mounted on such a flimsy metal plate that it
is almost impossible to put the actuator back on the valve and still have
moving parts at the end - the slightest overtightening of a screw, and
the whole thing distorts and nothing moves. "Grrr" - and worse, I said
many times as I struggled in a corner of a tight cupboard with a red hot
water cylinder, for hours to get it to work 'properly'. (Yes I emptied
the tank in the end; and yes; the water in the resulting bath was cold by
the time I was ready for it!)

Once it became mobile, another problem presented itself, in that, on
moving to the centre position from either side, an oscillating motion
tended to be set up with the motor driving its cam against the switch
arms/springs and being bounced rather than operating the switch that
turns it off. Click, click, click, click etc. It may well have been
this oscillation tendency which had burned the switch contacts
'prematurely'.

With much fiddling, I managed to - temporarily I expect - bend the switch
arms enough to correct the bounce, and get it all 'working'.

BUT what a load of crap for what a load of cash!

With this experience, I can say that, if I had had the old Danfoss
(really old) heavy duty gearing, and the Honeywell circuitboard switch
mounting method, I could have at least had an assembly that was easy to
get on and off and reasonably robust; with switches that could be
replaced occasionally. But why are they allowed to get away with still
using the same 'failure guaranteed' switches whilst charging prices which
ought to come with a lifetime guarantee?!

As I would imagine that numerous CH systems must be in a similar state -
unless I have just been extremely unlucky! - with many other people
throwing away money trying to solve 'circulation/air
lock/pump/thermostat' problems, unaware of the nature of these valve
actuators, I thought UK-Diy'ers might appreciate this tip.

With any luck some people reading this might save themselves from wasting
cash test-replacing non faulty parts of their systems.

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 just repaired one a couple of months ago, the switches cost about 90p
from Maplin and take five minutes to fit, they should last for millions of
operations but that's at room temp and they tend to be hot.

" five minutes to fit" !

Honeywell? Danfoss?
Don't know how the current Danfoss are fixed, but if you can unsolder a sw
from the Honeywell board and replace it in five minutes, I take my hat off
to you. Even with a desoldering 'gun' it took me at least that long to
clean the holes.
Also very impressed that you managed to line up the various cams and levers
while under spring tension, enough to get them back over the valve stem. As
it seems to be only the stem itself that keeps them in line I found this to
be very fiddly indeed.

Good luck with your millions of operations: my experience says you will need
to be doing this again in about 2 years.

Regards,

S

"spamlet" wrote in message
om...
A cautionary tale for those investigating probs with their central
heating:

A couple of years ago I finally tracked down a problem that had had
generations of visiting plumbers busy, in frenzied and expensive, radiator
bleeding / pump replacing exercises, all to no effect, at a friend's
house. On careful analysis it turned out to be the motorised valve
actuator (Danfoss) that was the culprit all along.

More specifically, it was due to the pair of crap semi-micro switches
inside the actuator, which perform an elaborate 'dance' with the motor to
wind the valve back and forth between the three port positions. As with
all contacts (like the equally crap ones in mouse buttons), they need
cleaning from time to time, but as these are fixed inside the actuator
assembly they are both difficult to get at, and even more difficult to
clean, or replace.

When the main one of these gets dirty and stops conducting, the valve
stops in the half-way position, and the room thermostat appears to have
packed up, as it 'ceases to turn the 'CH' off' because the water keeps
circulating even when it is apparently set at HW only. There is also less
pump power to the (wrongly shared) CH side, so people start trying to
rebalance/bleed etc. rads, and eventually start blaming the pump. The
last thing anyone seems to think of is the valve actuator for some reason
(possibly because they are so outrageously expensive!).

Back then, initially, I tried to just replace the switches, and did manage
a short term repair after replacing one of them: they are very cheap even
at Maplins. The other one soon failed, however, and the way it was
mounted led to the ancient plastic mounting plate breaking when I tried to
get it off.

So had to grit teeth and face up to buying a new valve/actuator assembly:
and thought I'd better do the valve as well while I was at it (which also
means more expensive/inhibitor, anti knock down the drain: if only I'd
thought to put a stop cock on the outlet to the ch system header tank
while I was at it...)

After extensive reading of these columns and those of the Screwfix Forum -
and some very silly stick from posters who simply would not believe that a
semi-micro switch could ever fail - I decided to opt for the more
expensive Honeywell V4073A valve and actuator which cost me £60.44 on 15
Nov 2005.

Up until now this seemed to have been a good buy: it had been easy to fit;
had what seemed like a clever ball arrangement rather than flaps in the
valve itself; and a quiet and smooth switching action.

However, I recently began to notice that the CH seemed to be on when it
should not be, so had a closer look yesterday: AND Lo!, inside are just
the same crap switches as in the Danfoss! At first, all seemed not lost,
as these ones were mounted on their own little circuit board, which could
be removed for easy working. Unfortunately, the way they were arranged,
they could not be opened for cleaning until one had been removed from the
board, but once open they were easy to clean the muck off the contacts.

In the Honeywell case however, there was the additional crapness of a
largish 12k resistor which had been dry jointed and was coming in at 20k
as a result, and overheating the circuit board to boot. So I had to
resolder this along with the cleaned switch.

Then the fun really started!
How they assembled the thing I don't know, but the actuating
cams/gears/springs etc, are mounted on such a flimsy metal plate that it
is almost impossible to put the actuator back on the valve and still have
moving parts at the end - the slightest overtightening of a screw, and the
whole thing distorts and nothing moves. "Grrr" - and worse, I said many
times as I struggled in a corner of a tight cupboard with a red hot water
cylinder, for hours to get it to work 'properly'. (Yes I emptied the tank
in the end; and yes; the water in the resulting bath was cold by the time
I was ready for it!)

Once it became mobile, another problem presented itself, in that, on
moving to the centre position from either side, an oscillating motion
tended to be set up with the motor driving its cam against the switch
arms/springs and being bounced rather than operating the switch that turns
it off. Click, click, click, click etc. It may well have been this
oscillation tendency which had burned the switch contacts 'prematurely'.

With much fiddling, I managed to - temporarily I expect - bend the switch
arms enough to correct the bounce, and get it all 'working'.

BUT what a load of crap for what a load of cash!

With this experience, I can say that, if I had had the old Danfoss (really
old) heavy duty gearing, and the Honeywell circuitboard switch mounting
method, I could have at least had an assembly that was easy to get on and
off and reasonably robust; with switches that could be replaced
occasionally. But why are they allowed to get away with still using the
same 'failure guaranteed' switches whilst charging prices which ought to
come with a lifetime guarantee?!

As I would imagine that numerous CH systems must be in a similar state -
unless I have just been extremely unlucky! - with many other people
throwing away money trying to solve 'circulation/air lock/pump/thermostat'
problems, unaware of the nature of these valve actuators, I thought
UK-Diy'ers might appreciate this tip.

With any luck some people reading this might save themselves from wasting
cash test-replacing non faulty parts of their systems.

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 just repaired one a couple of months ago, the switches cost about 90p from
Maplin and take five minutes to fit, they should last for millions of
operations but that's at room temp and they tend to be hot.

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

In message , spamlet
writes
A cautionary tale for those investigating probs with their central heating:



now, if you'd read the uk.d-i-y FAQ, ...




I'm not sure why you had such problems, I used to repair them some years
ago, not that difficult to repair


--
geoff

"spamlet" wrote in message
om...
A cautionary tale for those investigating probs with their central heating:

A couple of years ago I finally tracked down a problem that had had
snip tale of woe

I have had systems in two houses with Honeywell three way valve actuators,
up to ten years old. Never had a problem with the micro switches. Have had a
number of motors fail though. Always at an inconvenient time. Solved that by
buying an extra motor - never went wrong after that! After all the switches
only operate, say, 10 times a day , shouldn't be a problem. Certainly the
motor problem has been posted here several times but I don't recall hearing
about microswitch problems until now.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

On 7 May, 22:46, geoff wrote:
In message , spamlet
writes

A cautionary tale for those investigating probs with their central heating:

now, if you'd read the uk.d-i-y FAQ, ...

I'm not sure why you had such problems, I used to repair them some years
ago, not that difficult to repair

--
geoff

Poosibly a matter of dexterity and practice there Geoff.g
Anyway the OP has enjoyed a good whinge. Most right thinking folk
would have simply swapped the powerhead and enjoyed the rest of the
day free.

In an earlier contribution to this discussion,
spamlet wrote:

A cautionary tale for those investigating probs with their central
heating:
A couple of years ago I finally tracked down a problem that had had
generations of visiting plumbers busy, in frenzied and expensive,
radiator bleeding / pump replacing exercises, all to no effect, at a
friend's house. On careful analysis it turned out to be the motorised
valve actuator (Danfoss) that was the culprit all along.

SNIP

You can replace a Danfoss actuator for 30-odd quid - it just isn't worth
trying to fix them.

As others have said, the only *real* solution is to convert to an S-Plan
system, with two 2-port valves - which is what I've just done.

The problem with the 3-port valve is that it's too clever by half - and has
multiple modes of failure, many of which are not that easy to diagnose. In
particular, getting the thing to sit at the mid position without hunting
really challenges the laws of physics!
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

In article ,
"Roger Mills" writes:
As others have said, the only *real* solution is to convert to an S-Plan
system, with two 2-port valves - which is what I've just done.

The problem with the 3-port valve is that it's too clever by half - and has
multiple modes of failure, many of which are not that easy to diagnose. In
particular, getting the thing to sit at the mid position without hunting
really challenges the laws of physics!

There's no hunting in the mid position unless something's broken
or wasn't wired properly. The motor's rotor is locked in mid
position by feeding it DC (or half-wave rectified AC), which is
generated in the head by a diode in the circuit.

I am the first point of call for a number of heating systems
around my family. Most have a mid position valve and none have
failed. One's about 5 years old, and the others all at least
10 years old. They are a mixture of makes.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In an earlier contribution to this discussion,
Andrew Gabriel wrote:


There's no hunting in the mid position unless something's broken
or wasn't wired properly. The motor's rotor is locked in mid
position by feeding it DC (or half-wave rectified AC), which is
generated in the head by a diode in the circuit.


I have to admit that none of mine (and I've needed several in the last 18
years) have actually suffered from hunting, but several people have
mentioned hunting in recent threads - so it *does* appear to be a problem.

But the fact remains that the thing is overly complicated and seems prone to
more frequent failure than its 2-port cousin. One day when I've got nothing
better to do (so it may never happen!) I'll count up the number of CH
problem threads in uk.d-i-y where the ultimate diagnosis has pointed to a
problem with a 3-port valve. I shall need a lots of hands and feet to count
them!
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

In article ,
"Roger Mills" writes:
In an earlier contribution to this discussion,
Andrew Gabriel wrote:


There's no hunting in the mid position unless something's broken
or wasn't wired properly. The motor's rotor is locked in mid
position by feeding it DC (or half-wave rectified AC), which is
generated in the head by a diode in the circuit.

I have to admit that none of mine (and I've needed several in the last 18
years) have actually suffered from hunting, but several people have
mentioned hunting in recent threads - so it *does* appear to be a problem.

It's probably a symptom of some failure, such as one of
the contacts not working or the diode going open-circuit.
If I had some free time (not at the moment), I might sit
down and work out what could cause it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"The OP has enjoyed a good whinge. Most right thinking folk
would have simply swapped the powerhead and enjoyed the rest of the
day free."

"but I don't recall hearing about microswitch problems until now."

And, presumably, you don't want to hear about them?
You like forking out £60's every two years to buy the same faulty kit over
and over.


"There's no hunting in the mid position unless something's broken
or wasn't wired properly."

"It's probably a symptom of some failure, such as one of
the contacts not working"

Quite. :-(

I cannot claim wide experience of CH systems, but both those I have had to
look at, had had a lot of money thrown at them without identifying the
fault, before I sat down to try and sort them out myself, and both had
failed in exactly the same way due to exactly the same burned semi-micro
switches - of which I have pictures if anyone is still in doubt.

As I indicated, the majority of users are probably quite unaware when their
valves are not working properly: the rads and water still get hot when their
'on' cycles are lit: only the room thermostat gives the game away when it
appears to fail to override the programmer.

Trust these devices if you must.
I don't have the luxury of being able to afford to.
Perhaps there are some people reading uk.d-i-y who aren't moneyed experts
and this information might save them some time and money.
If there are no non-rich-experts using this forum, and anyone else who takes
the time to offer up useful information is just going to be sniped at, what
is it for?

S

In message , Spamlet
writes

Trust these devices if you must.
I don't have the luxury of being able to afford to.
Perhaps there are some people reading uk.d-i-y who aren't moneyed experts
and this information might save them some time and money.
If there are no non-rich-experts using this forum, and anyone else who takes
the time to offer up useful information is just going to be sniped at, what
is it for?

Ah, but if you'd looked here - in the uk.d-i-y FAQs

http://www.diyfaq.org.uk/plumbing/co...itionvalve.htm

The symptoms are well known to most regulars here, and a request would
prolly have brought a quick answer


p.s. it's a newsgroup, not a forum


--
geoff

"geoff" wrote in message
...
In message , Spamlet
writes

Trust these devices if you must.
I don't have the luxury of being able to afford to.
Perhaps there are some people reading uk.d-i-y who aren't moneyed experts
and this information might save them some time and money.
If there are no non-rich-experts using this forum, and anyone else who
takes
the time to offer up useful information is just going to be sniped at,
what
is it for?

Ah, but if you'd looked here - in the uk.d-i-y FAQs

http://www.diyfaq.org.uk/plumbing/co...itionvalve.htm

The symptoms are well known to most regulars here, and a request would
prolly have brought a quick answer

Thanks for the tip Geoff,

but as I, am sure like most people, just selected this news group from a
list provided by my service provider I had no idea there was any on line
version, with FAQs or anything else, and as the whole point of having a news
reader is to avoid having to go on line and use clumsy and pop up ridden web
based fora, I am not likely to have come across any FAQ's, as this defeats
the object of having a news reader!

Anyhow, I will now have a look, so cheers.

Might it be possible to organise a permanent post at the top of downloaded
news messages pointing out the parent site and its FAQs to any newcomers who
arrive by the same route as me?

S

In message , Spamlet
writes

"geoff" wrote in message
...
In message , Spamlet
writes

Trust these devices if you must.
I don't have the luxury of being able to afford to.
Perhaps there are some people reading uk.d-i-y who aren't moneyed experts
and this information might save them some time and money.
If there are no non-rich-experts using this forum, and anyone else who
takes
the time to offer up useful information is just going to be sniped at,
what
is it for?

Ah, but if you'd looked here - in the uk.d-i-y FAQs

http://www.diyfaq.org.uk/plumbing/co...itionvalve.htm

The symptoms are well known to most regulars here, and a request would
prolly have brought a quick answer

Thanks for the tip Geoff,

but as I, am sure like most people, just selected this news group from a
list provided by my service provider I had no idea there was any on line
version, with FAQs or anything else, and as the whole point of having a news
reader is to avoid having to go on line and use clumsy and pop up ridden web
based fora, I am not likely to have come across any FAQ's, as this defeats
the object of having a news reader!

Well, no it doesn't, the FAQ is there so that people don't keep on
asking the same questions which come up time and time again. Your post
more or less falls into this class.

If you read up on netiquette, you will find that one is advised to lurk
for a time to get a feeling for the group, which would have given you a
chance to see a pointer to the FAQs




Anyhow, I will now have a look, so cheers.

Might it be possible to organise a permanent post at the top of downloaded
news messages pointing out the parent site and its FAQs to any newcomers who
arrive by the same route as me?

S



--
geoff

In an earlier contribution to this discussion,
Spamlet wrote:

You like forking out £60's every two years to buy the same faulty kit
over and over.


I reckon that my Danfoss actuators have each worked reliably for at least 5
years - and not all failures have been due to micro-switches - the motor got
tired on the last one. I think the last replacement cost me about £35 - so
I'm not sure that I can really complain about a cost of £7 p.a.

I *have* taken some of the failed ones apart, and concluded that whereas I
*could* replace components, it was very fiddly and not really worth it.

I think the concensus is that these valves do cause *some* annoyance, but
are don't really merit the major rant which they received in your initial
post.

As others have said, 2-port valves seem to be more reliable (and are
certainly a lot less complicated). So maybe you should convert your system
to S-Plan to avoid having to keep replacing the 3-port valve. Even so,
2-port valves are not guaranteed to work for ever!
--
Cheers,
Roger
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