We seem to have a little problem.

CH is gas boiler (Potterton Netaheat), programmer has separately
selectable HW and CH times, and they are independent of each other.
System has pump, cylinder etc. remote from boiler, thermostat in
hallway.

Problem: the CH comes on even if thermostat is set to minimum. I then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way one
since we have independent control of CH and HW). I can't actually look
at the valve right now because it's in a room where SWMBO is asleep
after a bad night!

Are my assumptions correct? And is the valve the most likely culprit? If
I read the FAQ right, the most common failure mode is a burn out coil
leading to CH on all the time - is this correct?

--
Bob Eager
begin a new life...dump Windows!

"Bob Eager" wrote in message
...
We seem to have a little problem.

CH is gas boiler (Potterton Netaheat), programmer has separately
selectable HW and CH times, and they are independent of each other.
System has pump, cylinder etc. remote from boiler, thermostat in
hallway.

Problem: the CH comes on even if thermostat is set to minimum. I then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way one
since we have independent control of CH and HW). I can't actually look
at the valve right now because it's in a room where SWMBO is asleep
after a bad night!

Are my assumptions correct? And is the valve the most likely culprit? If
I read the FAQ right, the most common failure mode is a burn out coil
leading to CH on all the time - is this correct?


Not my field either, but I have experienced the same problem. In my case it
was the valve actuator, a Drayton. It appears to have a synchronous motor
and various gears and microswitches made of polycrackathene and crapite. The
gears had worn and were slipping. You may find that the valve has a lever
with which you can disengage the valve from the actuator and set the
position manually, You could try manually exercising the valve just in case
it's got sticky, and also verify that the system works correctly with the
valve position manually set. I'm quite possibly wrong, but I think that the
valve actuators are widely available as separate items. Just make sure you
make a detailed diagram of which wire goes where when you remove the old
one.

HTH,
Steve S

On 9 Aug 2004 08:29:29 GMT, "Bob Eager" wrote:

We seem to have a little problem.

CH is gas boiler (Potterton Netaheat), programmer has separately
selectable HW and CH times, and they are independent of each other.
System has pump, cylinder etc. remote from boiler, thermostat in
hallway.

Problem: the CH comes on even if thermostat is set to minimum. I then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way one
since we have independent control of CH and HW). I can't actually look
at the valve right now because it's in a room where SWMBO is asleep
after a bad night!

OK....... Of course we're all dying to know why, but are too polite
to ask.


Are my assumptions correct? And is the valve the most likely culprit? If
I read the FAQ right, the most common failure mode is a burn out coil
leading to CH on all the time - is this correct?

Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.




..andy

To email, substitute .nospam with .gl

On Mon, 9 Aug 2004 10:09:43 UTC, Andy Hall wrote:

at the valve right now because it's in a room where SWMBO is asleep
after a bad night!

OK....... Of course we're all dying to know why, but are too polite
to ask.

Small boy with nosebleeds!

Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.

Thanks....that was what I was thinking. Test meter no problem - have
several!

--
Bob Eager
begin a new life...dump Windows!

On 9 Aug 2004 10:23:32 GMT, "Bob Eager" wrote:

On Mon, 9 Aug 2004 10:09:43 UTC, Andy Hall wrote:

at the valve right now because it's in a room where SWMBO is asleep
after a bad night!

OK....... Of course we're all dying to know why, but are too polite
to ask.

Small boy with nosebleeds!

Oh dear. If it's persistent, try Vaseline to keep the area moist,
otherwise it's ENT visit with silver nitrate on a stick. Sounds worse
than it is, but all a bit upsetting for a small child.

I have that T-shirt......



Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.

Thanks....that was what I was thinking. Test meter no problem - have
several!

Obviously if the valve does seem sticky, this is a good time to check
out the system thoroughly, by draining, flushing etc. I've posted a
method of how to do this a few times.

..andy

To email, substitute .nospam with .gl

On Mon, 9 Aug 2004 10:09:43 UTC, Andy Hall wrote:

On 9 Aug 2004 08:29:29 GMT, "Bob Eager" wrote:
Problem: the CH comes on even if thermostat is set to minimum. I then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way one
since we have independent control of CH and HW).

Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.

Hmm. Further examination indicates that, even with the CH part turned
off at the programmer, water flows out of both ports of the 3 way valve.
As might be expected given the symptoms.

HOWEVER....the CH pump is also running....! Surely that would indicate a
fault in the control system rather than the valve - or have I missed
something?
--
Bob Eager
begin a new life...dump Windows!

"Bob Eager" wrote in message
...
On Mon, 9 Aug 2004 10:09:43 UTC, Andy Hall wrote:

On 9 Aug 2004 08:29:29 GMT, "Bob Eager" wrote:
Problem: the CH comes on even if thermostat is set to minimum. I then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way one
since we have independent control of CH and HW).

Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.

Hmm. Further examination indicates that, even with the CH part turned
off at the programmer, water flows out of both ports of the 3 way valve.
As might be expected given the symptoms.

HOWEVER....the CH pump is also running....! Surely that would indicate a
fault in the control system rather than the valve - or have I missed
something?
--

Probably not a fault in the control system. Our system (like many, I
suspect) uses pump for both HW and CH.

You may have a relay box into with the wire from the valve actuator
disappear. You could try listening for the relay clicks as you turn on and
off HW and CH (various combinations). If there are relays in there you could
also try cleaning the contacts and checking the coil continuity, after first
isolating the mains supply.

Steve S

On Mon, 9 Aug 2004 13:07:22 UTC, "SteveS"
wrote:

"Bob Eager" wrote in message
...
On Mon, 9 Aug 2004 10:09:43 UTC, Andy Hall wrote:

On 9 Aug 2004 08:29:29 GMT, "Bob Eager" wrote:
Problem: the CH comes on even if thermostat is set to minimum. I then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way one
since we have independent control of CH and HW).

Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.

Hmm. Further examination indicates that, even with the CH part turned
off at the programmer, water flows out of both ports of the 3 way valve.
As might be expected given the symptoms.

HOWEVER....the CH pump is also running....! Surely that would indicate a
fault in the control system rather than the valve - or have I missed
something?
--

Probably not a fault in the control system. Our system (like many, I
suspect) uses pump for both HW and CH.

Ours doesn't. The pump is on the downstream side of the CH port of the 3
way valve. I should have made that clear. Looks like it's to assist CH
circulation, but cylinder is gravity fed.

You may have a relay box into with the wire from the valve actuator
disappear. You could try listening for the relay clicks as you turn on and
off HW and CH (various combinations). If there are relays in there you could
also try cleaning the contacts and checking the coil continuity, after first
isolating the mains supply.

Thanks...will investigate further but still wonder about that running
pump.

--
Bob Eager
begin a new life...dump Windows!

"Bob Eager" wrote in message
...
On Mon, 9 Aug 2004 13:07:22 UTC, "SteveS"
wrote:

"Bob Eager" wrote in message
...
On Mon, 9 Aug 2004 10:09:43 UTC, Andy Hall wrote:

On 9 Aug 2004 08:29:29 GMT, "Bob Eager" wrote:
Problem: the CH comes on even if thermostat is set to minimum. I
then
turned the CH off completely at the programmer (in other words,
disabling the timer) and STILL the rads get hot. However, if I turn
the
HW off at the programmer too, the rads cool down.

Now, this isn't my area at all, but I would suspect either the
programmer or the electrically operated valve (presumably a 3-way
one
since we have independent control of CH and HW).

Either a burnt out motor or sticky valve or gooed up with grot.

You can take the head off of the valve and check whether or not the
motor runs (you can buy the motors separately). Then test the
valve
base, trying to turn it. If stiff, your culprit is there.
It could be a microswitch in the valve head, but less likely. That
needs a test meter to check out.

Hmm. Further examination indicates that, even with the CH part turned
off at the programmer, water flows out of both ports of the 3 way
valve.
As might be expected given the symptoms.

HOWEVER....the CH pump is also running....! Surely that would indicate
a
fault in the control system rather than the valve - or have I missed
something?
--

Probably not a fault in the control system. Our system (like many, I
suspect) uses pump for both HW and CH.

Ours doesn't. The pump is on the downstream side of the CH port of the 3
way valve. I should have made that clear. Looks like it's to assist CH
circulation, but cylinder is gravity fed.

You may have a relay box into with the wire from the valve actuator
disappear. You could try listening for the relay clicks as you turn on
and
off HW and CH (various combinations). If there are relays in there you
could
also try cleaning the contacts and checking the coil continuity, after
first
isolating the mains supply.

Thanks...will investigate further but still wonder about that running
pump.


Could still mean that the valve actuator is at fault. My guess is that the
pump will not turn off until the valve is actually at the HW only position,
as determined by the microswitches in the actuator.

Steve S

On Mon, 9 Aug 2004 13:39:00 UTC, "SteveS"
wrote:

Thanks...will investigate further but still wonder about that running
pump.


Could still mean that the valve actuator is at fault. My guess is that the
pump will not turn off until the valve is actually at the HW only position,
as determined by the microswitches in the actuator.

Aha. Good point...!

--
Bob Eager
begin a new life...dump Windows!