Radiator only hot at the top when bled

[dynomikered]

Hi wondering if anyone can help me with this problem. I moved a radiator for my mother-inlaw in the summer but when she puts the heating on it is the only one that does not get warm(stone cold ). I thought it needed bleeding but when i bled it only water came out,after about 5 mins of bleeding the top of the rad gets warm . when i put the screw back in after 5 mins it goes cold again. It is a maual TRV . Could it be that the flow and return are the wrong way round as when the rad is bled the pipework to the lock shield valve gets hot but the pipework to the manual TRV stays stone cold. and as with the top of the rad the pipework goes cold when the bleeding is stoped
any help would be much appreciated
cheers
mike

 

[Slugbabydotcom]

Could it be that the flow and return are the wrong way round

Yes look closely at the valve and you will see an arrow which should indicate the direction of flow. If this arrow points both ways then its a bidirectional valve and it will be more likely that the pin is stuck in it, leaving the valve in the closed position.
Other than that it could be an airlock or blockage on the pipe leading to the trv. Close the lockshield valve off and see if you can bleed water out as you did before.

 

[dynomikered]

Sorry when i said a manual trv what i mean is it's a manual valve that u turn to open or closed not the ones with settings on i.e 1,2,3,4,5(the new ones) so i dont think it has a pin in it

 

[MANDATE]

You have two valves which are of the same type. One used for ON/OFF the other preset to regulate the flow (lockshield).
I would suggest that the lockshield valve is almost closed which would restrict the flow. best to start with the lockshield fully open and then close it down according to temperture desired. Or If the radiator still only gets hot at the top when both valves are fully open, then it is due to sludge which has lodged along the base of the radiator and prevents water from passing up/down the waterways.

 

[dynomikered]

The rad only gets hot at the top when it is bled(only water comes out) and the pipe work to the lock shield gets warm.so what you are saying is it could be two things 1, lock shield valve and the on-off valve could be conected the wrong way round i.e flow to the lock shield and return to the on off valve, or 2, there could be sludge in the return side causing the rad to stay cold. But untill the rad is bled the pipe work on both flow and return is stone cold
thanks 4 staying with me on this much appreciated
cheers
mike

 

[mmalone]

The rad only gets hot at the top when it is bled(only water comes out) and the pipe work to the lock shield gets warm.so what you are saying is it could be two things 1, lock shield valve and the on-off valve could be conected the wrong way round i.e flow to the lock shield and return to the on off valve, or 2, there could be sludge in the return side causing the rad to stay cold. But untill the rad is bled the pipe work on both flow and return is stone cold
thanks 4 staying with me on this much appreciated
cheers
mike

sounds to me like its sludged up !!!

 

[dynomikered]

Thanks 4 the reply but if it was sludge why would the flow pipe work only get hot when it was bled( the pipe work is about a meter long)should it not be hot up to the valve all the time the heating is on.
thank 4 all the advice, just trying to eliminate every thing be for i go in all guns blazing

 

[MANDATE]

The On/Off valve and the lockshield valve are the same. One has a knob to turn it, the other usually stays put at about half open. When you bleed the rad, one valve is fully open and the other is partially open (or supposed to be ). You can try having one closed and one open and bleed the rad then reverse the situation. If you have a blocked valve you won't get any water out if one is closed and the other blocked.
Sludge in the radiator blocks the waterways in the middle so water may well go up one side along the top and down the other side.
Before refitting a radiator it pays to (a) flush it out and (b) run of a bucket ful of water from each of the valves.

 

[dynomikered]

Hi me agin, have bled raidator as explained with one valve closed and one open on both sides but water is coming out of both, so no blockage have also tried shuting off emersion tank and closing weel valve then draining raidiator to see if air locked but now all downstirs rads are cold,
then tried balencing closed all rad except the one that was cold but still no joy please help as mother inlaw not happy
cheers
mike

 

[MANDATE]

Not sure I follow what's happening now. You've bled the rad with lockshield open and control valve closed and again with control valve open and lockshield closed. In both cases water exits the bleed valve. This means both the lockshield and the control valve are ok. So why drain radiator to see if air locked. Anyhow air in a radiator rises and prevents the top from getting hot, but if it's been bled then the top will get hot.
Sludge will settle at the bottom and could prevent water circulating and create cold areas usually at the bottom.
It now seems you've got an additonal problem if all rads downstairs are cold and you may have created this, if you have drained the system partially.
You need to ensure the pump is running and air has been bled from it. A pump turning in air will have no effect on the water. It is also possible a pocket of air has been created in the pipework which would be a genuine airlock. When the pump pushs water against a pocket of air the air compresses and there is no flow of water. This pocket of air has to be released but refuses to budge because the resistance is too much and opening a radiator bleed valve will not solve it.
Turning up the temperture and pump speed may help, but I found by removing a radiator and running off some water from each valve allows airlock to disperse.

 

[PEDANTICVINDICTIVEMAN]

If she is getting hypothermic you will have to remove hers and your clothing and rub your body against hers to stop her needing hoispital treatment, thing is you may need therapy and hospital treatment yourself afterwards for trauma, other than that call in a pro.

 

[Nige F]

Went straight to your post,PVM