"TheScullster" wrote in message
...
First of all thanks to John Rumm and Set Square for previous related
assistance.

snip

So I have one or two questions:

Does the fact that the heating is off mean the motorised valve is closed
and therefore flow will be lower from the flow side valves anyway?
OR
Would the make up water (which is teed into the return from the hot water
cylinder) pass from the return to the flow side in the rest of the system,
so that flow from either valve on bleeding should be approximately equal?


It may affect the ability to remove an airlock. Most motorized valves have a
lever on the side which allows one to put the valve into a manual "drain"
position in the absence of power, to cover the situation you are describing.
It would be worth removing the boxing and trying that.


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

Central Heating - Expert Assistance Required - Revisited Again
 

First of all thanks to John Rumm and Set Square for previous related
assistance.

Last night I tried to bleed one radiator and one towel rail both of which
struggle to manage warm when the rest in the house are reasonable temp (both
fed from same plastic 15mm feed).

With the following result:

First of all the towel rail:

Attached hose to top connection and opened each valve in turn.
With only the return valve open I get reasonable flow from the hose.
Closing the return valve and opening the flow valve, I get much less flow so
I suspect the valve is stuck closed(ish).

Next the Bedroom Rad

Tried the same process - remove bleed connection and attach hose.
Same thing occurs, good flow with return valve open, good trickle only when
only flow valve is open.


Presumably this suggests either an air lock or blockage rather than two
blocked valves.
The motorised valve for the heating side is boxed in and not accessible.
But I wanted the heating off before messing last night.

So I have one or two questions:

Does the fact that the heating is off mean the motorised valve is closed and
therefore flow will be lower from the flow side valves anyway?
OR
Would the make up water (which is teed into the return from the hot water
cylinder) pass from the return to the flow side in the rest of the system,
so that flow from either valve on bleeding should be approximately equal?


If this is an air lock, any tricks on how to clear this?
On recommendation, I tried leaving the valve open at both the towel rail and
rad (one at a time not simultaneously) for a while to bleed out the air
lock, but didn't get more than a steady trickle!

So what next?
Any suggestions gratefully received

TIA

Phil

In an earlier contribution to this discussion,
TheScullster wrote:

First of all thanks to John Rumm and Set Square for previous related
assistance.


Does the fact that the heating is off mean the motorised valve is
closed and therefore flow will be lower from the flow side valves
anyway?

Yes, if the motorised valve is closed, it will certainly make it difficult
to get any water to the rad on the flow side.

Remind me, are we talking about an S-Plan system with separate 2-port valves
for CH and HW? If so, you somehow need to open the CH valve - either using
its manual lever or electrically. You clearly don't want the heating on
while you do it - so if you go for the electrical option (because the valve
is difficult to access physically) you'll need to disable the boiler and
pump and *then* turn on the heating.

[If it's a Y-Plan system with a single 3-port valve, you'll need to force
the valve to either the mid or CH position. Again you have manual or
electrical options, depending on which is easier]

As a matter of interest, have you run the system after your less than 100%
successful attempt to bleed it. If so, was there any improvement?
--
Cheers,
Set Square
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TheScullster wrote:

Attached hose to top connection and opened each valve in turn.
With only the return valve open I get reasonable flow from the hose.

That ought to eliminate the plastic pipe, and the amount of head the
system has from the equation then...

Closing the return valve and opening the flow valve, I get much less flow so
I suspect the valve is stuck closed(ish).

snip

The motorised valve for the heating side is boxed in and not accessible.
But I wanted the heating off before messing last night.

So I have one or two questions:

Does the fact that the heating is off mean the motorised valve is closed and
therefore flow will be lower from the flow side valves anyway?

Yes - probably. It will depend on the type of valve, but a solenoid
driven valve will close on removal of power, as will a sprung motorised
one.

OR
Would the make up water (which is teed into the return from the hot water
cylinder) pass from the return to the flow side in the rest of the system,
so that flow from either valve on bleeding should be approximately equal?

If you think about it, with the valve closed the only path from make-up
water to flow side of the rad is collectively through the other rads by
drawing water out of their feed connections.

If this is an air lock, any tricks on how to clear this?
On recommendation, I tried leaving the valve open at both the towel rail and
rad (one at a time not simultaneously) for a while to bleed out the air
lock, but didn't get more than a steady trickle!

One solution is using mains cold water from a hose to force water back
into the affected pipes. You need to be sure that there is a clear path
back to the vent before doing this though. The water you force in should
end up in the header tank ultimately.

So what next?
Any suggestions gratefully received

I get the impression that the motorised valve is looking like one
suspect - does it feed all of the rads, or just the problem ones?

--
Cheers,

John.

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

"Set Square" wrote:


Remind me, are we talking about an S-Plan system with separate 2-port
valves
for CH and HW?

Yes S Plan


If so, you somehow need to open the CH valve - either using
its manual lever or electrically.

Whilst it will mean unboxing, I am inclined to go the manual route as the
current wiring arrangment is a bit hairy!

You clearly don't want the heating on while you do it

Wouldn't this maybe help to move an air lock with the pump running and the
motorised valve open?


As a matter of interest, have you run the system after your less than 100%
successful attempt to bleed it. If so, was there any improvement?


Bit late finishing last night, so not sure if there has been any change.
I would be very suprised if there had, as the bleed rate didn't improve from
either rad or towel rail during test.

Thanks again

Phil

"John Rumm" wrote:


That ought to eliminate the plastic pipe, and the amount of head the
system has from the equation then...

True

a solenoid driven valve will close on removal of power, as will a sprung
motorised one.

I thought as much


One solution is using mains cold water from a hose to force water back
into the affected pipes. You need to be sure that there is a clear path
back to the vent before doing this though. The water you force in should
end up in the header tank ultimately.


Have you tried this yourself?


I get the impression that the motorised valve is looking like one
suspect - does it feed all of the rads, or just the problem ones?


No there is only one motorised valve on the CH side so this isolates all
rads.
As I think I may have mentioned many mails ago, this was making some nasty
noises some months ago, so may be presenting more restriction than it
should. Maybe this, combined with the reduced 15mm pipe size upstairs is
causing the pump over.

Unfortunately we have visitors this weekend so I don't think I will be
allowed to start unboxing in the dining room to expose the problem valve.
This treat may have to wait till next week.

Thanks again for help


Phil

In an earlier contribution to this discussion,
TheScullster wrote:

"Set Square" wrote:


You clearly don't want the heating on while you do it

Wouldn't this maybe help to move an air lock with the pump running
and the motorised valve open?

I was thinking from the point of view that, if you're bleeding a lot of
water out of the rad, you don't want this to be uncomfortably hot. On second
thoughts, it *may* help to bleed with the system running - at least the
valve should then be open, and the pump should be adding a bit more urge. If
you try this, I would turn the boiler stat down quite low to avoid getting
scalded.
--
Cheers,
Set Square
______
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In an earlier contribution to this discussion,
TheScullster wrote:

As I think I may have mentioned many mails ago, this was making some
nasty noises some months ago, so may be presenting more restriction
than it should. Maybe this, combined with the reduced 15mm pipe size
upstairs is causing the pump over.


I wouldn't have thought so. With an S-Plan system, the *valve* switches the
boiler and pump on - and only does so once it's fully open. Also, I presume
that the valve is on the *output* side of the pump so that, if the valve
*were* creating a restriction, it would be throttling the flow and making it
*less* likely to pump over.

Another random thought: I have never tried this but it *might* work. You
said that, when trying to get some flow through the problem radiators, if
you turned off the other rads and turned up the pump speed, the system then
started pumping over but *still* didn't heat the problem rads.

Unless anyone comes up with a compelling reason why it is a *bad* idea, I
would then try temporarily (for a couple of minutes or so) bunging up the
vent pipe with a cork. This would stop the pump-over and would give the flow
nowhere else to go other than through the problem rads - and might just
clear any air locks which exist. [The air should collect in the top of the
rads concerned, where it can be bled out]. Worth a try?
--
Cheers,
Set Square
______
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TheScullster wrote:

One solution is using mains cold water from a hose to force water back
into the affected pipes. You need to be sure that there is a clear path
back to the vent before doing this though. The water you force in should
end up in the header tank ultimately.



Have you tried this yourself?

Never had a need to... Had to do it once many years ago on my mum's hot
water cylinder though.

My vented system (when I had it) only got drained twice in my
recollection - once to move a rad, and it refilled ok after that, and
the second time when I ripped it out! (it did not ever recover from that!)

I get the impression that the motorised valve is looking like one
suspect - does it feed all of the rads, or just the problem ones?



No there is only one motorised valve on the CH side so this isolates all
rads.
As I think I may have mentioned many mails ago, this was making some nasty
noises some months ago, so may be presenting more restriction than it
should. Maybe this, combined with the reduced 15mm pipe size upstairs is
causing the pump over.

Could be... in fact I would suspect the valve contributing more than the
pipe - the pipe is probably just tipping the balance.

Unfortunately we have visitors this weekend so I don't think I will be
allowed to start unboxing in the dining room to expose the problem valve.

Funny things women ;-)

This treat may have to wait till next week.

Something to look forward to then...

(handy tip, small metal detector thingies are quite good for working out
where the screws are hidden under filler and paint on boxed in pipes etc)

--
Cheers,

John.

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

"Set Square" wrote:

I was thinking from the point of view that, if you're bleeding a lot of
water out of the rad, you don't want this to be uncomfortably hot. On
second
thoughts, it *may* help to bleed with the system running - at least the
valve should then be open, and the pump should be adding a bit more urge.
If
you try this, I would turn the boiler stat down quite low to avoid getting
scalded.


Think I'll try this option first, before stripping out to find motorised
valve!

Thanks

Phil

"Set Square" wrote:


I presume that the valve is on the *output* side of the pump so that, if
the valve
*were* creating a restriction, it would be throttling the flow and making
it
*less* likely to pump over.

Yes I believe so. I think the system has pumped return through the boiler,
then the heating mot valve straight after.
Again this is all covered by boxing, but I am fairly confident that's the
layout.


Unless anyone comes up with a compelling reason why it is a *bad* idea, I
would then try temporarily (for a couple of minutes or so) bunging up the
vent pipe with a cork. This would stop the pump-over and would give the
flow
nowhere else to go other than through the problem rads - and might just
clear any air locks which exist. [The air should collect in the top of the
rads concerned, where it can be bled out]. Worth a try?

Sounds a touch hairy for my liking.
Without electrical jiggery pokery, it will be necessary for the boiler to be
running and heating the water for the pump to run and valve to open.
Sounds like it may pressurise the system generally?

Phil

"John Rumm" wrote:

I would suspect the valve contributing more than the pipe - the pipe is
probably just tipping the balance.


Set Square's point about the switch making only when the valve is fully open
would tend to dispute this.
Unless the valve can be so damaged/worn that the switch can make without the
valve internals opening correctly.


Funny things women ;-)


Actually the visitors are 3 (yes three!) French boys about 10 yrs old. A
return exchange trip for my lad's visit earlier this year.
Where did I put that French phrase book?


(handy tip, small metal detector thingies are quite good for working out
where the screws are hidden under filler and paint on boxed in pipes etc)


Nice one!


Thanks again John

Phil

In an earlier contribution to this discussion,
TheScullster wrote:

"Set Square" wrote:

I was thinking from the point of view that, if you're bleeding a lot
of water out of the rad, you don't want this to be uncomfortably
hot. On second
thoughts, it *may* help to bleed with the system running - at least
the valve should then be open, and the pump should be adding a bit
more urge. If
you try this, I would turn the boiler stat down quite low to avoid
getting scalded.


Think I'll try this option first, before stripping out to find
motorised valve!

Thanks

Phil

On further thought, it's probably best to do the flow side with the pump
running, and the return side without.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In an earlier contribution to this discussion,
TheScullster wrote:

"Set Square" wrote:


Unless anyone comes up with a compelling reason why it is a *bad*
idea, I would then try temporarily (for a couple of minutes or so)
bunging up the vent pipe with a cork. This would stop the pump-over
and would give the flow
nowhere else to go other than through the problem rads - and might
just clear any air locks which exist. [The air should collect in the
top of the rads concerned, where it can be bled out]. Worth a try?

Sounds a touch hairy for my liking.
Without electrical jiggery pokery, it will be necessary for the
boiler to be running and heating the water for the pump to run and
valve to open.
Sounds like it may pressurise the system generally?

Phil

Can you turn your boiler right off on it's own stat - so that it doesn't
fire even when given a demand? [Mine will do that] If so, you can simply
circulate cold water while you do this dastardly deed. I don't think you
need to worry about pressurising the system - the pump generates damn all
pressure in absolute terms because it only needs to overcome flow resistance
rather than having to lift water to a great height. [A typical CH pump only
produces about 0.5 bar even when running stalled at its highest speed]
--
Cheers,
Set Square
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TheScullster wrote:

I would suspect the valve contributing more than the pipe - the pipe is
probably just tipping the balance.



Set Square's point about the switch making only when the valve is fully open
would tend to dispute this.
Unless the valve can be so damaged/worn that the switch can make
without the
valve internals opening correctly.

Yes, in fact I expect he is right thinking about it... so unless the
valve is also partially blocked with debris of some sort, you can
discount what I said.

Funny things women ;-)



Actually the visitors are 3 (yes three!) French boys about 10 yrs old. A
return exchange trip for my lad's visit earlier this year.
Where did I put that French phrase book?

I was thinking more along the lines of the rhetorical question and tone
of voice that goes with: "you are not going to start pulling the house
apart _now_ are you"?


--
Cheers,

John.

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