A mostly old Y plan system....
Symptoms of dwindling circulation occurred, lower rads not heating, upstairs output tailing off then the system quit entirely. Boiler said dry fire error, it was filled but presumably no circulation. Filter has been emptied of muck, pump has been opened & is clear. What else is likely to have failed the circlation? The 3 way valve isn't blocking rad flow in HW only mode, but getting the bottom part of it off the pipework to fit a new ball looks like a right mare of a job. Access is terrible & the pipework around it allows it no movement afaics. I don't see that causing the problem.
Clues welcome, right now I lack one!


NT

On 27/03/2019 20:31, wrote:
A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem. Clues welcome, right now I lack one!

What's "dry fire error"?

What's the rate of flow on the HW side? How hot does it get?

Does the HW get hot when just CH is demanded?

Can you hear air/cavitation when the pump is running?

I think there is a lot of analysis still to do.

On Wednesday, 27 March 2019 20:47:16 UTC, Fredxx wrote:
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem. Clues welcome, right now I lack one!

What's "dry fire error"?

boiler thinks it fired with no water, ie temp shot up fast

What's the rate of flow on the HW side? How hot does it get?

there's no primary circuit flow. It's not a combi

Does the HW get hot when just CH is demanded?

there's no primary circuit flow. It's not a combi, so HW cyl was cold until immersion used.

Can you hear air/cavitation when the pump is running?

will check tomorrow.

I think there is a lot of analysis still to do.

Surely. I just was left very puzzled today when I found the pump not blocked.


NT

On 28/03/2019 00:42, wrote:
On Wednesday, 27 March 2019 20:47:16 UTC, Fredxx wrote:
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem. Clues welcome, right now I lack one!

What's "dry fire error"?

boiler thinks it fired with no water, ie temp shot up fast

What's the rate of flow on the HW side? How hot does it get?

there's no primary circuit flow. It's not a combi

I meant on the HW primary circuit.

Does the HW get hot when just CH is demanded?

there's no primary circuit flow. It's not a combi, so HW cyl was cold until immersion used.

So no circulation at all, including HW cylinder primary. Earlier you
said, "The 3 way valve isn't blocking rad flow in HW only mode" implying
there was flow here?

Can you hear air/cavitation when the pump is running?

will check tomorrow.

I think there is a lot of analysis still to do.

Surely. I just was left very puzzled today when I found the pump not blocked.

Any evidence it turns? Perhaps a cap gone bad.

Also one can feel the pipe and see how far the heated water gets.

Sounds like sludge.
I hate CH.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Fredxx" wrote in message
...
On 27/03/2019 20:31, wrote:
A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem. Clues welcome, right now I lack one!

What's "dry fire error"?

What's the rate of flow on the HW side? How hot does it get?

Does the HW get hot when just CH is demanded?

Can you hear air/cavitation when the pump is running?

I think there is a lot of analysis still to do.

On 27/03/2019 20:31, wrote:
A mostly old Y plan system....
Symptoms of dwindling circulation occurred, lower rads not heating, upstairs output tailing off then the system quit entirely. Boiler said dry fire error, it was filled but presumably no circulation. Filter has been emptied of muck, pump has been opened & is clear. What else is likely to have failed the circlation? The 3 way valve isn't blocking rad flow in HW only mode, but getting the bottom part of it off the pipework to fit a new ball looks like a right mare of a job. Access is terrible & the pipework around it allows it no movement afaics. I don't see that causing the problem.
Clues welcome, right now I lack one!


NT


Are you sure the system is correctly filled with water and there are no
airlocks?

I've seen the symptoms you describe once (without the electronic
warnings), on a neighbours system which was all but empty- the gate
valve from the header tank was closed. When I opened it and bled the
radiators, all was well.

--
Always smile when walking, you never know where there is a camera ;-)

Remarkable Coincidences:
The Stock Market Crashes of 1929 and 2008 happened on the same
date in October. In Oct 1907, a run on the Knickerbocker Trust
Company led to the Great Depression.

On Thursday, 28 March 2019 09:46:25 UTC, Brian Gaff wrote:
"Fredxx" wrote in message
...
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem. Clues welcome, right now I lack one!

What's "dry fire error"?

What's the rate of flow on the HW side? How hot does it get?

Does the HW get hot when just CH is demanded?

Can you hear air/cavitation when the pump is running?

I think there is a lot of analysis still to do.

Also one can feel the pipe and see how far the heated water gets.

Sounds like sludge.
I hate CH.
Brian

less than a foot from the boiler.


NT

On Thursday, 28 March 2019 10:00:38 UTC, Brian Reay wrote:
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system....
Symptoms of dwindling circulation occurred, lower rads not heating, upstairs output tailing off then the system quit entirely. Boiler said dry fire error, it was filled but presumably no circulation. Filter has been emptied of muck, pump has been opened & is clear. What else is likely to have failed the circlation? The 3 way valve isn't blocking rad flow in HW only mode, but getting the bottom part of it off the pipework to fit a new ball looks like a right mare of a job. Access is terrible & the pipework around it allows it no movement afaics. I don't see that causing the problem.
Clues welcome, right now I lack one!


NT


Are you sure the system is correctly filled with water and there are no
airlocks?

I've seen the symptoms you describe once (without the electronic
warnings), on a neighbours system which was all but empty- the gate
valve from the header tank was closed. When I opened it and bled the
radiators, all was well.

I drained it, a lot came out. Not sure what else I can say. I'll check out the pump some more today.


NT

On 27/03/2019 20:31, wrote:
A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem.

Clues welcome, right now I lack one!

Blockage or airlock sounds the most likely. You could start with a drain
down and refill. If that does not help, then a mains water flush
(temporarily block the vent and F&E pipes).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thursday, 28 March 2019 10:35:51 UTC, John Rumm wrote:
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem.

Clues welcome, right now I lack one!

Blockage or airlock sounds the most likely. You could start with a drain
down and refill. If that does not help, then a mains water flush

nod

(temporarily block the vent and F&E pipes).

puzzled by that bit though


NT

On 28/03/2019 10:45, wrote:
On Thursday, 28 March 2019 10:35:51 UTC, John Rumm wrote:
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem.

Clues welcome, right now I lack one!

Blockage or airlock sounds the most likely. You could start with a drain
down and refill. If that does not help, then a mains water flush

nod

(temporarily block the vent and F&E pipes).

puzzled by that bit though

If you are (for example) injecting mains water into a disconnected rad
tail, and draining from the other, you want all the flow to go through
the pipework and rads, not to be forced into the F&E tank where it might
overwhelm the overflow.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thursday, 28 March 2019 13:18:15 UTC, John Rumm wrote:
On 28/03/2019 10:45, tabbypurr wrote:
On Thursday, 28 March 2019 10:35:51 UTC, John Rumm wrote:
On 27/03/2019 20:31, tabbypurr wrote:

A mostly old Y plan system.... Symptoms of dwindling circulation
occurred, lower rads not heating, upstairs output tailing off then
the system quit entirely. Boiler said dry fire error, it was filled
but presumably no circulation. Filter has been emptied of muck, pump
has been opened & is clear. What else is likely to have failed the
circlation? The 3 way valve isn't blocking rad flow in HW only mode,
but getting the bottom part of it off the pipework to fit a new ball
looks like a right mare of a job. Access is terrible & the pipework
around it allows it no movement afaics. I don't see that causing the
problem.

Clues welcome, right now I lack one!

Blockage or airlock sounds the most likely. You could start with a drain
down and refill. If that does not help, then a mains water flush

nod

(temporarily block the vent and F&E pipes).

puzzled by that bit though

If you are (for example) injecting mains water into a disconnected rad
tail, and draining from the other, you want all the flow to go through
the pipework and rads, not to be forced into the F&E tank where it might
overwhelm the overflow.

Ah, got ya.

Update:
Today I set the room stat to minimum so the boiler didn't fire & switched the system on. Previously I found the pump wasn't getting power from the boiler, so temporarily rewired its live to permanent live so it runs all the time, which would at least get the thing running. So the pump's been on. It's definitely spinning, I can hear that clearly & can hear bubble or cavitation type noises.

However... the primary circuit & downstairs rads are all cold, despite running through the HW cylinder that's hot from the immersion. So I can only conclude that primary circuit water is not flowing thru the HW cyl heat exchanger. Why I don't know.

The system was drained & refilled the other day. The plastic header tank connected by copper pipes contains a LOT of rust pieces & dust. The system is nearly 40 years old and I don't know whether there has been an increase in recent times in rust deposition. A magnetic filter was fitted 2 years ago.

Oh, when it first went wrong I discovered the header tank overtaken with biofouling. That has gone without a trace now, the chemicals wiped it out.

So something somewhere has to be blocked. I guess the first moves to make are to blast what I can with mains water & to add cleaning chemical. However this system had all the rads flushed out 2 years ago & has been cleaner chemicalled a few times... it plainly hasn't solved it. I'm beginning to think the only solution is to take all the plumbing apart & blast every bit out.. I hate the thought of doing that though.

PS one downstairs drain points drains freely, the other barely manages to dribble.


NT

On 28/03/2019 19:52, wrote:
Update:
Today I set the room stat to minimum so the boiler didn't fire & switched the system on. Previously I found the pump wasn't getting power from the boiler, so temporarily rewired its live to permanent live so it runs all the time, which would at least get the thing running. So the pump's been on. It's definitely spinning, I can hear that clearly & can hear bubble or cavitation type noises.

Just to be on the safe side, you might check that the pump is actually
pumping. That would be one thing checked off. If you could swap in a
known-working pump from somewhere else, or plumb this one into a test
circuit?

On Thursday, 28 March 2019 22:08:14 UTC, GB wrote:
On 28/03/2019 19:52, tabbypurr wrote:

Update:
Today I set the room stat to minimum so the boiler didn't fire & switched the system on. Previously I found the pump wasn't getting power from the boiler, so temporarily rewired its live to permanent live so it runs all the time, which would at least get the thing running. So the pump's been on. It's definitely spinning, I can hear that clearly & can hear bubble or cavitation type noises.

Just to be on the safe side, you might check that the pump is actually
pumping. That would be one thing checked off. If you could swap in a
known-working pump from somewhere else, or plumb this one into a test
circuit?

I'm not sure how. But I'm also not sure how it would fail to pump given that it's making all the right noises, fizzy ones as well as spinny ones. I checked its ports were clear.


NT

On 27/03/2019 20:31, wrote:
A mostly old Y plan system....
Symptoms of dwindling circulation occurred, lower rads not heating, upstairs output tailing off then the system quit entirely. Boiler said dry fire error, it was filled but presumably no circulation. Filter has been emptied of muck, pump has been opened & is clear. What else is likely to have failed the circlation? The 3 way valve isn't blocking rad flow in HW only mode, but getting the bottom part of it off the pipework to fit a new ball looks like a right mare of a job. Access is terrible & the pipework around it allows it no movement afaics. I don't see that causing the problem.
Clues welcome, right now I lack one!


NT


My central heating boiler water pump failed recently. I did find that
when I removed the screw in the middle alot of water came out because
the rotor was loose. The pump was vibrating slightly but not doing
nything useful. I was a bit slow to realize that the pump was faulty.
When I tried to buy a replacement I was told that they just had the
heads in stock, which actually proved very easy to change.


--
Michael Chare

On 28/03/2019 22:08, GB wrote:
On 28/03/2019 19:52, wrote:
Update:
Today I set the room stat to minimum so the boiler didn't fire &
switched the system on. Previously I found the pump wasn't getting
power from the boiler, so temporarily rewired its live to permanent
live so it runs all the time, which would at least get the thing
running. So the pump's been on. It's definitely spinning, I can hear
that clearly & can hear bubble or cavitation type noises.

Just to be on the safe side, you might check that the pump is actually
pumping.Â* That would be one thing checked off. If you could swap in a
known-working pump from somewhere else, or plumb this one into a test
circuit?

Those were my thoughts, but NT was initially giving mixed signals of
whether there was flow into the HW cylinder primary, or not.

I think its time to take off the pump and see if it run. If it has a
screw on the end of the rotor on its removal it should be possible to
see it turn under power.

Of course all the vanes could be missing, which is likely given the
tales of gunk in a very old system. I've seen an old BMC water pump
otherwise working ok, missing its vanes, causing the engine to overheat.

On Thursday, 28 March 2019 22:48:53 UTC, Fredxx wrote:
On 28/03/2019 22:08, GB wrote:
On 28/03/2019 19:52, tabbypurr wrote:

Update:
Today I set the room stat to minimum so the boiler didn't fire &
switched the system on. Previously I found the pump wasn't getting
power from the boiler, so temporarily rewired its live to permanent
live so it runs all the time, which would at least get the thing
running. So the pump's been on. It's definitely spinning, I can hear
that clearly & can hear bubble or cavitation type noises.

Just to be on the safe side, you might check that the pump is actually
pumping.Â* That would be one thing checked off. If you could swap in a
known-working pump from somewhere else, or plumb this one into a test
circuit?

Those were my thoughts, but NT was initially giving mixed signals of
whether there was flow into the HW cylinder primary, or not.

no there's certainly no flow there. If there were it'd extract DHW cylinder heat & send it to the rads at low level.

I think its time to take off the pump and see if it run. If it has a
screw on the end of the rotor on its removal it should be possible to
see it turn under power.

I know it turns. The noises indicate it does, it doesn't just hum.

Of course all the vanes could be missing, which is likely given the
tales of gunk in a very old system. I've seen an old BMC water pump
otherwise working ok, missing its vanes, causing the engine to overheat.

This pump is 2 years old, has a plastic rotor with narrow water passages & the rotor is pristine & there's no blockage or debris there. The rotor turns without problem. I really don't believe it's the pump.

I plan to mains water blast the drain point that only dribbles. It might be worth taking that rad outside to flush it, it's not been there very long but if there's no flow I guess that rad is the prime place debris would collect.

I must fit a valve to the header tank, mucking with it in the loft is a pita.


NT

On 28/03/2019 23:22, wrote:

This pump is 2 years old, has a plastic rotor with narrow water passages & the rotor is pristine & there's no blockage or debris there. The rotor turns without problem. I really don't believe it's the pump.

Then, it's a blockage in the system. Hopefully, mains pressure will
clear that, but otherwise you have a bit of a job.

On Thursday, 28 March 2019 23:33:17 UTC, GB wrote:
On 28/03/2019 23:22, tabbypurr wrote:

This pump is 2 years old, has a plastic rotor with narrow water passages & the rotor is pristine & there's no blockage or debris there. The rotor turns without problem. I really don't believe it's the pump.

Then, it's a blockage in the system. Hopefully, mains pressure will
clear that, but otherwise you have a bit of a job.


Another update. There is certainly primary flow. It can be heard loud & clear from the filter. That means there's air in there, which is odd since from the filter it flows through the boiler then through a pot with F&E pipes out the top, and it's been running much of the day. But it's running.

The boiler is still displaying F72 fault code, NTC sensors out of range, though they've been replaced. It won't fire up. So it's looking like a PCB problem and a blocked HW cyl heat exchanger. Sounds expensive :/


NT

On 28/03/2019 22:48, Fredxx wrote:
On 28/03/2019 22:08, GB wrote:
On 28/03/2019 19:52, wrote:
Update:
Today I set the room stat to minimum so the boiler didn't fire &
switched the system on. Previously I found the pump wasn't getting
power from the boiler, so temporarily rewired its live to permanent
live so it runs all the time, which would at least get the thing
running. So the pump's been on. It's definitely spinning, I can hear
that clearly & can hear bubble or cavitation type noises.

Just to be on the safe side, you might check that the pump is actually
pumping.Â* That would be one thing checked off. If you could swap in a
known-working pump from somewhere else, or plumb this one into a test
circuit?

Those were my thoughts, but NT was initially giving mixed signals of
whether there was flow into the HW cylinder primary, or not.

I think its time to take off the pump and see if it run. If it has a
screw on the end of the rotor on its removal it should be possible to
see it turn under power.

Of course all the vanes could be missing, which is likely given the
tales of gunk in a very old system. I've seen an old BMC water pump
otherwise working ok, missing its vanes, causing the engine to overheat.

My VW Passat started to overheat whenever the car went up a hill. When I
eventually took the car to pieces I found that the plastic impellor had
completely disintegrated. I was pleased with the replacement as that had
a metal impellor.


--
Michael Chare

On 28/03/2019 23:22, wrote:

This pump is 2 years old, has a plastic rotor with narrow water passages & the rotor is pristine & there's no blockage or debris there. The rotor turns without problem. I really don't believe it's the pump.

We have just changed a pump. Though it would spin much of the time, it
appears there was a 'flat spot' on it from which, if it came to rest on
that, it could not restart.

--
F

If it's a grundfos pump they occasionally shear the shaft and while the end of the shaft under the top plug spins the impeller doesn't.
Don't know what make of motorised valve you have but seizure of the spindle can and does a happen. Also some models permit removal of the top plate without removal from the pipework. Just beware losing the o ring seal.

On Monday, 1 April 2019 08:15:56 UTC+1, Cynic wrote:
If it's a grundfos pump they occasionally shear the shaft and while the end of the shaft under the top plug spins the impeller doesn't.
Don't know what make of motorised valve you have but seizure of the spindle can and does a happen. Also some models permit removal of the top plate without removal from the pipework. Just beware losing the o ring seal.

that 2nd bit's handy to know!


NT