Folks,

I'd appreciate your thoughts. Long story short:

Just moved into house with an Alpha CD32C boiler in attic and 9 rads.
Eight of these work fine.

The ninth radiator stays cold, no matter what setting the TRV's on. The
'needle' in the TRV seems OK (up and down by some millimetres when
pressed manually) so I tried bleeding the radiator. A *lot* of air came
out. Even better news, without any 'glooping' sounds - as one might
expect if sludge were being pushed about - the rad started warming up!

Unfortunately, the bleeding caused the water pressure to drop too low
and the boiler shut down. I re-pressurised, started the boiler up again
and ...eight rads work and the bedroom one doesn't.

I've now bled every rad in the house twice, but no change. Eight are
fine, one isn't.

Have I missed something depressingly obvious?


Thanks,
Peter

P.S. I've also tried running the system with all rads closed down
except the bedroom one. No change. *sigh*

In an earlier contribution to this discussion,
Peter Kemp wrote:

Folks,

I'd appreciate your thoughts. Long story short:

Just moved into house with an Alpha CD32C boiler in attic and 9 rads.
Eight of these work fine.

The ninth radiator stays cold, no matter what setting the TRV's on.
The 'needle' in the TRV seems OK (up and down by some millimetres when
pressed manually) so I tried bleeding the radiator. A *lot* of air
came out. Even better news, without any 'glooping' sounds - as one
might expect if sludge were being pushed about - the rad started
warming up!

Unfortunately, the bleeding caused the water pressure to drop too low
and the boiler shut down. I re-pressurised, started the boiler up
again and ...eight rads work and the bedroom one doesn't.

I've now bled every rad in the house twice, but no change. Eight are
fine, one isn't.

Have I missed something depressingly obvious?


Thanks,
Peter

P.S. I've also tried running the system with all rads closed down
except the bedroom one. No change. *sigh*

Assuming that both sides of the radiator are actually connected into the
system (have you checked the pipework?) it sounds as if one of the valves is
turned off, stuck shut or silted up. Have you checked that the lockshield
isn't turned off? If so, have you bled each side in turn? [In other words,
open the TRV and shut off the lockshield, and bleed. Then repeat the process
with the TRV shut (preferably with the supplied plastic cap in place of the
thermostatic head) and the lockshield open.] You should get a good flow of
water from each side. [Before bleeding, set the CH zone valve to the manual
position - or the 3-port valve to the mid-position, depending on what you
have.]
--
Cheers,
Roger
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Roger Mills wrote:
In an earlier contribution to this discussion,
Peter Kemp wrote:

Have I missed something depressingly obvious?


Thanks,
Peter

P.S. I've also tried running the system with all rads closed down
except the bedroom one. No change. *sigh*

Assuming that both sides of the radiator are actually connected into
the system (have you checked the pipework?) it sounds as if one of
the valves is turned off, stuck shut or silted up. Have you checked
that the lockshield isn't turned off?

I'd also give the TRV (the metal part at least) a bit of a wallop.
Irrespective of the movement of the pin the valve jumper can stick on the
valve seat inside the TRV.

Tim

Peter Kemp wrote:
Folks,

I'd appreciate your thoughts. Long story short:

Just moved into house with an Alpha CD32C boiler in attic and 9 rads.
Eight of these work fine.

The ninth radiator stays cold, no matter what setting the TRV's on. The
'needle' in the TRV seems OK (up and down by some millimetres when
pressed manually) so I tried bleeding the radiator. A *lot* of air came
out. Even better news, without any 'glooping' sounds - as one might
expect if sludge were being pushed about - the rad started warming up!

Unfortunately, the bleeding caused the water pressure to drop too low
and the boiler shut down. I re-pressurised, started the boiler up again
and ...eight rads work and the bedroom one doesn't.

I've now bled every rad in the house twice, but no change. Eight are
fine, one isn't.

Have I missed something depressingly obvious?


The need for perseverance, and a trick

Turn the pump on flat out, and shut down every rad in the house on the
balancing valves except the cold one.

Then bleed and keep bleeding.

It took me about 4 days to fully get the air out of a new installation.

Every time you repressure the boiler, air will come in in the water, and
that has to be bled again.


Thanks,
Peter

P.S. I've also tried running the system with all rads closed down
except the bedroom one. No change. *sigh*

"Peter Kemp" wrote

Folks,

I'd appreciate your thoughts. Long story short:

Just moved into house with an Alpha CD32C boiler in attic and 9 rads.
Eight of these work fine.

The ninth radiator stays cold, no matter what setting the TRV's on. The
'needle' in the TRV seems OK (up and down by some millimetres when
pressed manually) so I tried bleeding the radiator. A *lot* of air came
out. Even better news, without any 'glooping' sounds - as one might
expect if sludge were being pushed about - the rad started warming up!

Unfortunately, the bleeding caused the water pressure to drop too low
and the boiler shut down. I re-pressurised, started the boiler up again
and ...eight rads work and the bedroom one doesn't.

I've now bled every rad in the house twice, but no change. Eight are
fine, one isn't.

Have I missed something depressingly obvious?


Thanks,
Peter

P.S. I've also tried running the system with all rads closed down
except the bedroom one. No change. *sigh*

If all else fails (and bleeding the rad using each valve in turn is good
advice) - close both valves, drain and remove rad.
Check for sludgy stuff in rad and flush out till clean.
Then (not sure about pressurised system method as I have open vented) open
the offending rad valves in turn with suitable bowl handy and make sure you
get decent flow. I suspect you may need someone to add water through the
fill loop at this point if the problem rad is highest to check that both
valves allow free flow. If nothing comes out of either valve, then you have
either got a valve replacement job or a blockage.

I had a similar problem with 2 rads. Turned out there was some magnetite
(main constituent of sludge) moving around, which stopped at a rad valve and
completely blocked it. Sorted this by part opening the valve and
"broggling" through the valve with a tie-wrap to clear the block until water
flowed out. You should be able to see the internals of the valve operating
by looking from the radiator connection end IYSWIM. As others have said you
will need a plastic cap-type operating head for the TRV. Obviously need
some dexterity juggling valves, tie-wraps and bowl here (plenty of towels
advisable).

If you have similar blockage issues, make sure you fire through plenty of
water into a bowl to clear all remnants.


HTH

Phil

Wow - some really helpful input and suggestions: much obliged.

I've re-bled all the radiators in the system. Each one now spits water
the instant I turn the bleed valve, including the recalcitrant beastie,
so I guess I can't blame an airlock.

Time for a slightly more 'assertive' approach, methinks...


Thanks everyone,
Peter

"Peter Kemp" wrote in message
om...
Wow - some really helpful input and suggestions: much obliged.

I've re-bled all the radiators in the system. Each one now spits water
the instant I turn the bleed valve, including the recalcitrant beastie,
so I guess I can't blame an airlock.

Time for a slightly more 'assertive' approach, methinks...


Thanks everyone,
Peter

The last time I came across this the lockshield valve was broken. It felt as
if it was opening and closing but internally the valve had snapped and it
was sat in the closed position.

Adam