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Jan 12, 2013
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I wonder if anyone can help with this...

One radiator circuit is constantly hot even though the room stats are not calling for heat. So the rad circuit is being fed with hot wat er from the manifold if (for example) the hot water cylinder is calling for heat.

I suspected a stuck valve so I have removed the motor head. The 2-port valve seems to be open regardless of the spindle position. The spindle does not feel loose at all. Is it possible for the internal ball to be stuck in the 'on' position even if the spindle is in the 'closed' (11 to 5) position?

Any suggestions welcome! Tim
 
The 2-port valve seems to be open regardless of the spindle position. The spindle does not feel loose at all.
The spindle should turn easily, just using your fingers, but only a few degrees, say from 11 to 1 on a clock. If you can't turn it by hand, try lubricating the spindle seal. A silicon lubricant is best, but a little WD40 will do.
 
The spindle should turn easily, just using your fingers, but only a few degrees, say from 11 to 1 on a clock. If you can't turn it by hand, try lubricating the spindle seal. A silicon lubricant is best, but a little WD40 will do.

The spindle does turn, it's just that the valve doesn't seem to close at the end of the travel. Is it possible that the spindle can become detached from the ball inside?
 
If the boiler is firing with no demand it sounds like the auxiliary switch is stuck in the closed position therefore creating a circuit , is there power on the orange wire ?
 
If the boiler is firing with no demand it sounds like the auxiliary switch is stuck in the closed position therefore creating a circuit , is there power on the orange wire ?
The boiler is firing due to demand from the hot water cylinder. That causes heated water to flow through the radiator circuit's valve. The problem is that I can't seem to close the valve even with the motor head removed.
 
The boiler is firing due to demand from the hot water cylinder. That causes heated water to flow through the radiator circuit's valve. The problem is that I can't seem to close the valve even with the motor head removed.

Sorry miss read , are you sure its all HW demand . Yes reading again it sounds like the rubber ball has come off and stuck , looks like a drain down and a new one .
 
Sorry miss read , are you sure its all HW demand . Yes reading again it sounds like the rubber ball has come off and stuck , looks like a drain down and a new one .
Thanks. I'd wondered if that was possible for the ball to come off the spindle. It sounds like you're confirming that it is.
 
We've had one come off and go down the 22mm before now. Was blocking the whole system, got a fair bit down too!
 
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Are you sure the rads are not getting hot through the poor circuit design (what use to be called the 3rd Tee rule)?
Are all the rads getting hot, do they start heating via the return on the upstairs rads normally the ones closes to the HW cylinder?
 
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If your valve has a small bump on the actuator cover, the ball and 'O ring' can be replaced. It's part no 272752A/U CARD and cost about £10. You will still have to drain down to below the level of the valve.
 
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Could be a design fault .Hot water return should be last tee before boiler .There may be a heating circuit return pipe in between hot water return and boiler causing the water to back circulate.
Could fit non return valve if pipework difficult to alter .
 
Could be a design fault .Hot water return should be last tee before boiler .There may be a heating circuit return pipe in between hot water return and boiler causing the water to back circulate.
Could fit non return valve if pipework difficult to alter .
Thanks but I'm sure that the valve is the problem here.
 

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