Central heating problem after draining/filling system.

[JJC001]

I drained my central heating system to remove s couple of pipes that used to feed a radiator that has not been on the wall since moving into the house. The pipes were t'd in so I simply removed the T joints and reconnected the pipes with some straight connectors. I then refilled the system by turning on the water to the expansion tank in the loft and bled as many of radiators as possible. Everything seemed to be ok but:

1: The radiator in one of the bedrooms is warm at the bottom but not at the top. I cannot find a bleed valve on it anywhere. Not at the sides or the along the top at the back. There is a circular lump in what I would consider to be a normal position but there is no valve attached. Is this usual and if not how can I bleed it?

2: The radiaror in the bathroom remains cold. The pipes feeding it on both sides are hot but the radiator remains cold. I have bled it and there is only water coming out. Yes I have made sure the valves are on. Any ideas?

3: There are two radiators on the ground floor that have both been bled but remain cold (as do the pipes that feed them)!

All the other radiators are fine. Do I need to bleed the pump or anywhere else other then the radiators? Sometimes I can hear what sounds like water trickling in the pipes is this indicating anything?

The boiler also feeds the hotwater tank and this all seems fine so I am now at a loss at to what I should do.

Thanks

[Set Square]

It is most unusual for a radiator not to have a bleed screw. Some are in "unlikely" places! Can you post a reference to a of photo of it, to see whether anyone recognises it and can tell you where the bleed screw is?

With regard to the radiators which don't get hot, you have an air lock in one of the supply pipes. They still bleed ok, because the water comes via the other pipe. The usual cure for this is to turn off all other radiators except each of the problem ones in turn - so that all the water is forced through just one radiator. You may also need to increase the pump speed while you do this. This usually clears the air lock.

If this doesn't work, bleed each of the rad's pipes separately. Turn off one valve so that water can only come in via the other pipe, and bleed quite a lot of water (several pints) out of the bleed screw. Then swap to the other valve and repeat. [If your system has been balanced, note the number of turns required to close the lockshield valve, so that it can be returned to the same position].

HTH.

[Tim Mitchell]

In article , JJC001 writes

The lump is a little plastic cap, the bleed screw is recessed in a hole.

[Dave Plowman (News)]

It may, but it's often just easier to 'pump' in mains pressure water via the drain valve. Of course making sure you don't overfill the header tank.

It's the only way I can do it with mine. ;-)

[JJC001]

Thanks all for the advice, a few turning off/on of various radiators and bleeding them a few more times has resulted in some success. I can confirm that the lump is a little plastic cap but alas still no bleed valve. Perhaps the people who installed the radiator got lazy and didn't put a bleed valve where the plastic plug is?

[Tim Mitchell]

In article , JJC001 writes

Have you peered down inside the hole? There should be a little square peg in the bottom of the hole which is the end of the bleed screw.

[D]

I think you might have misunderstood what Tim Mitchell meant. You remove that white plastic cap - it's just a cover for the bleeding valve. Lift it out and insert your key.

[JJC001]

You are both right, the little plastic cap was indeed a cover for the bleed valve, the only radiator in the house to have a cap over the bleed valve but I still feel stupid for not realising. Thanks all for your help, much appreciated!