Cold radiator

[beginner]

Two years ago I had my CH system powerflushed. Since then I've had problems with one radiator and now its totally cold. Inlet and outlet pipes are also cold - and there's no TRV. I've taken the rad off and completely flushed and, upon replacing, it begins to get hot and then goes completely cold again. Friends have suggested a kinked microbore pipe leading to the rad which may have collected sludge since powerflush. Any ideas?

 

[kevplumb]

kinked pipe

you have just answered your own question

 

[breezer]

Any ideas?

have you got microbore?
(you dont say you havent, but you dont say you have)

 

[ChrisR]

Try removing rad then running plenty of water out of each pipe. If that is ok you may have an air lock - close all rads except for this one.

A bit of managed water mains power is quite good for shifting blockages.

 

[beginner]

Try removing rad then running plenty of water out of each pipe. If that is ok you may have an air lock - close all rads except for this one.

A bit of managed water mains power is quite good for shifting blockages.

Thanks - tried letting the pipes run - the return flows freely but the supply just trickles

 

[bathjobby]

Outside tap adaptors (the ones that screw onto an outside tap to give you a spout that the hose push connects onto) are the same size and thread as the rad valves. Therefore you can screw them onto the rad valve once the rad is removed. Then connect hose to cold water mains and let the pipe have it (having got all the air out of the hose first), you can get a hose connector that automatically closes when you pull it off the connector, these are best because you turn the tap on, press your finger in the connector until all the air is out of the hose, then just snap it onto the valve connector for a couple of secs then pull it off again. If it is merely blocked this is usually enough to shift it so only do a little at first so that when you remove hose from valve, the sludge will run out rather than you blasting it around your CH pipework. This worked for all my blocked 10mm microbore except one. This produced a 'screaming' noise coming from a few feet away, turned out this was the water trying to get through a flattened section of the microbore pipe. Pipe replaced; bingo.

 

[beginner]

Thanks.....I'll try this and post the results!

 

[beginner]

now have two cold radiators - one in bathroom which appears to be on different 'circuit' from other. Have taken both radiators off and flushed completely with cold mains water - until running completely clear. Also let pipes run with rads removed - piping hot water spurting from supply and cold water trickling from return on both.

When i put the rad back on it gets very hot (and air escapes from bleed valve) but after a while it seems that circulation stops and the things go cold again. All other radiators on system are piping hot - no cold spots and all bled successfully so no other probs.

What could be wrong?

 

[Bahco]

Rad valves could not be opening fully if you are sure there is no blockage.
Might be worth changing them and balancing your system. Do a search but the rule is the nearer the rad to the boiler the less the valve needs to be open.