1 cold radiator

[joncox]

I, too, have just one cold rad in the house. It's in the kitchen, by the boiler. The pump and tank are of course upstairs. All other rads in the house work well and are balanced.

Both inflow and outflow pipes are hot; the rad is always full of water and doesn't need bleeding. Draining the rad using the drain hole at the base releases hot, clean water and the radiator heats up immediately. However, it cools down (as a cup of hot tea would) over an hour or so and then won't heat up at all.

Any suggestions?

 

[MANDATE]

A number of thoughts come to mind.
I wouldn't rule out the radiator, I think a radiator could still have a blockage yet be full of water and show no sign or air when bleeding.
If you closed the valves each side of radiator and removed it for cleaning it would establish whether or not there is a good flow through it.
It could explain how both inlet and outlet pipes are still hot.

If the problem is not the radiator, then I would think there is a resistance in the pipe work in the form of blockage or air lock.
An air lock is difficult to remove if there is no bleed valve in the appropriate position. I would close down all the other radiators to see if the pump can force water through the problem radiator.

I dealt with a similar problem some time ago, a radiator had been removed and replaced with a new one, but the new one did not get hot although it was full of water and free from air.
The radiator was removed and replaced this time with clear plastic tubing with a tap connector at each end and it was clear to see there was no flow across the tubing.
It was considered there was an air lock, but I did not know which side of the radiator. Using the tubing I ran off about 3 bucket full of water from each side. This proved successful, I could now see the water flowing through the tubing with air bubbles which meant other radiators would have to be bled. After closing both valves the new radiator was replaced and with valves open radiator was OK

 

[COG]

As you said the rad was beside the boiler ,have you visable checked the flow and return pipes do they feed into the rest of your heating system or direct to the boiler. you did not say if it worked in the past or if you inhereted the problem.

 

[joncox]

For everyone's amusement. The problem is with the rad itself, which is different and newer than the others in the house. The new one has tappings on the back, so there's no chance of using the flexible injector pipe which is key to getting a twin-entry valve microbore system radiator to circulate correctly.

There's 2 answers - get hold of a replacement rad to which I can fit an injector pipe (which means rooting through skips, basically) or running a length of copper pipe to the other end of the radiator to convert it.

Thanks for replies though.

 

[silester]

please help me one of my rads is also stone cold while the rest are hot. I've taken the rad off the wall and noted that the one pipe (the one with the heating control on it) does so much as let the water flow but trickle. how can I solve this as its driving me mad