Central Heating Radiator

[joe.s-b]

I have a radiator which has been turned off for a long time. It is now turned on. How long do I need to wait until it gets hot. The input pipe is hot and the output is also hot but all the radiator water is cold. Do I need to bleed off the cold water or just wait?

[BRIGHT SPARK]

Are both valves open? If they are and a thermostatic head is on one valve ..it may be that this valve is jammed due to it not being used for a while.Give it a sharp tap on the lower metal bit with a SMALLISH hammer it may release it.

[BRIGHT SPARK]

It could also require bleeding.

[buildersmate]

If both inlet and output pipes are hot, BS, that suggests there's nought wrong with the valves as water is passing through them.
Which surely leads to the conclusion that the radiator is largely full of air, and needs bleeding at its top.

[bhg481]

Could be air or could be black oxide if there's no rust-inhibitor in the system.

[PankySmooch]

Or as I've done with mine, give the rad a good wallop to remove any gunk that's lodged in it

[BRIGHT SPARK]

If the pipe is close to the circ the pipe could be hot.

[joe.s-b]

Thank you so far. There is no air in the system it bleeds clear water. I think that either the input valve of the TCV is stuck and as I am too old to get down onto the floor to fix it and am no longer dexterous I will call someone in.

[The Builder]

Be prepared Joe, if you get someone in, that he may have to do no more than unscrew the head of the TRV and tap the pin lightly.

It can happen that, if the pipe runs from rad to main circuit are very short, heat is conducted along them rather than any actually flowing through the rad.

The TRV is the first thing I would go for.

[joe.s-b]

thank you all. I had turned on the input valve with pliers without success but as Builder said I removed the cover of the control valve to find the pin was loose. So I prised off the plastic cove of the input valve to find it had stripped and not turned the control nut so I tuned the but with a spanner and lo and behold I have a not radiator. I pushed the plastic cover back on for cosmetic reasons and that was that. My advanced age seems to have prevented any sensible thought and I'm not sure what to do about that. Obviously try the answer bank and jog my grey cells. Thanks for all the advice and all have a festive Christmas.

[The Builder]

Ah... so it's not a TRV then, Joe, but a plain manual valve?

Yes, the plastic knob does occasionally strip. No matter how much you turn it... nothing happens.