"Lobster" wrote in message
...
John Edgar wrote:

Thanks for all the help and I am going to get them replaced. However I
think the problem on this particular radiator is something else. It
has a semi-circle that is cool, from bottom left to bottom right and
not quite to the top. The rest is hot. Very strange and I wonder what
it could be. I have opened the balancer valve 1/2 a turn with no
effect. Could there be air locked into it and if so how does one
remove it when it isn't actually at the bleeder hole?


This is caused by a radiator being plumbed with two bottom connections and at
a VERY slow flow rate (inadequate pump or valves nearly completely shut, or
whole system not balanced, or any combination of these) The hot water trickles
up from the feed valve across the top and then down the far side being pushed
by the water flowing in behind it, little mixing and inertia. Obviously cool
water next to its path gets warmed a little thereby giving an approximately
hemi-spherical cool patch in the middle.

Nick