1 radiator stays cold

[fill1974]

Hi, My kitchen radiator stays cold when all the others in the house are warm. We used to have a 1000mm radiator but we reduced it to a 300mm and now the new radiator wont warm up. I've tried bleeding it, adjusting the lockshield valve and thermostat valve, i've replaced both valves, i've rebalanced the system but still no luck. the water that comes out of the radiator is clear but cold (when the heating is on) when I shut the lock sheild and thermostat valves on all the radiators in the house one of the pipes on the none working radiator gets warm but the other pipe stays cold as does the radiator, please help

 

[Mike2007]

Try cracking open the valve tail on the "cold" side with cold side shut down and drain water into a kitchen basin + old towels. Keep the "hot pipe" valve open, draining from opposite side of rad.
If you drain the rad and water just stops, tap the "hot pipe" valve with spanner a little, might be stuck on seat.
Water should fill and should be hot, close coupling on valve. If you have a drain cock incorporated into the rad valve, use that to drain.

 

[fill1974]

Hiya, thanks for the quick reply. Just before i read your post i tried closing the hot pipe valve(which i assume is the inlet?)and leaving the cold pipe vavle open(the outlet?). I then trid to bleed the air out using a key from the top of the radiator, however hardly any water or air came out. Does this mean the cold pipe could be blocked? Also it was the cold pipe that was replaced/extended as we reduced the size of the radiator.

 

[Mike2007]

You need to work out which side is not flowing but locking down one side and cracking open the other valve, let out water.
Use washing-up bowl, they are good for catching it. You might find once you tried this on both sides and tightened it all back up it starts to warm and flow through after bleeding.
So you are removing rad water first, then letting water out of the system on one pipe only to check flow.