Radiator/TRV/Balance?

[Doug99]

Hi All.

A radiator is only getting luke warm whilst all the others get hot. How can I establish the potential cause between a defective TRV or a balance of the system?
The room its situated in is cold so the TRV should be fully open.

Cheers

Doug

 

[terryplumb]

Assuming you have bled the radiator of any air ,remove the TRV actuator head and see if the centre pin in the valve body moves freely . It should spring up ( a few millimetres) after pressing it down. Leave the actuator off ,and see if there is any difference.
If not ,it may be a balancing issue.

 

[BlueLoo]

Or sludge....

Radiators don't "unbalance" themselves overnight unless little hands are involved.

If it were sludge, you'de likely have a cold bottom and hot head.
Probs TRV is borked. Don't assume its the valve either, the heads don't last forever.

 

[Doug99]

The plunger moves ok. Should the TRV be fitted on the inlet or outlet side of the radiator?
Its currently fitted on the inlet end of the radiator.

 

[DP]

On the radiator in question, is one of the pipes to the radiator hot as other radiators?

 

[DP]

The plunger moves ok. Should the TRV be fitted on the inlet or outlet side of the radiator?
Its currently fitted on the inlet end of the radiator.

on some valves it matters, on most does not; refer to the valve literature.

 

[BlueLoo]

The plunger moves ok. Should the TRV be fitted on the inlet or outlet side of the radiator?
Its currently fitted on the inlet end of the radiator.

I checked all my TRVs this winter. Of the dozen or so i had, all of the valves were ok, but only two of the heads were serviceable.
Particularly, if i were to put pressure on the pin in the head, with the head in the OFF position, the inners would either fall away because the internal structures were shot or the pin was jammed in the ON position.

Just remove the head of your TRV, make sure the valve pin is moving freely (it is according to your post) so the rad should heat up if the lockshield valve has not been fiddled with.

If the rad is still cold, then you've no flow and something else is a miss (i would suggest sludge but that's but one of many reasons).

 

[Doug99]

The inlet (TFV) is hot and the outlet cold. The radiator only gets warm.
I have tried it with the outlet valve partial/half/fully open but no difference.
When I bleed it, the water coming out is dirty, so could be sludge?
All other house rads bleed clean water.

 

[BlueLoo]

The inlet (TFV) is hot and the outlet cold. The radiator only gets warm.
I have tried it with the outlet valve partial/half/fully open but no difference.
When I bleed it, the water coming out is dirty, so could be sludge?
All other house rads bleed clean water.

Sludged up.

Remove the rad and hose it out in the back yard.

And then think about the other rads which will probably follow suit.

Its easy enough to drain down the system, remove the rads and flush them out.

YouTube is your friend here.

 

[terryplumb]

Remove the rad and open the TRV to see if it gives a full flow of water ,then close it and do the same on the lockshield. If your system is sealed / pressurised ,keep pressure topped up.
If both valves flow fully ,suspect the rad and flush it ,outside with a hosepipe.