Radiator warm / cold

[ipbr21054]

I noticed the radiator plug which has the bleed valve in was driipping.
Ive turned both taps on the side down / off.
Removed the plug & applied some ptfe.
Plug refitted & valves opened up.

Turned on heating and all radiators in house are nice but this one is warm at the top and cold towards the botton.
Nothing like the others,when you walk in the room you can feel it aint working right.
Ive checked the boiler & put some water in.
Ive opened up the valve but no air just clean water.
Radiator is say 2 years old.

Any advice please.

 

[omega015]

This problem could indicate sludge in the radiator, which would need flushing out professionally but as its only a single radiator it might not be that. It could be a balancing issue. Is this radiator far away from the boiler (in terms of pipework)?

Worth a try.... could you try turning off all the other radiators except this one and run the central heating and see if the problem still exists. If so, try opening the lockshield valve a bit more so that there's a greater flow of water going into this radiator.

The lockshield typically looks like this (not a TRV with numbers on):

EDIT: don't open the lockshield too much, 1 full turn open from closed is way more than enough. Typically you do small incremental adjusts to balance each radiator.

 

[ipbr21054]

Hi,
It is only this radiator.
One side the radiator has that thermostat vale & the other just like the photo you supplied.
The radiator is say 12ft away from the boiler but as the pipes are under the floor boards im not sure the exact run,is that good enough ?

When you say turn off all other radiators does that mean both vales etc either side the radiators ?

If the problem is still there what does that indicate ?

If the problem has gone & radiator heats up what does that tell you ?

You say open up lockshield valve a little, my lockshield valve has a hard plastic cap which you turn,not just dust cover in photo you supply.
Having said that the valve in unscrewed all the way at present ?

Also for you info,when the heating was on and all the other radiators were hot this radiator was as below.
Pipe which enters lockshield valve was hot but the other side of the lockshield valve was tepid warm.
Pipe which leaves the thermostat valve at other end of radiator was cold.
Radiator bottom cold & top warm ish.

I will try this tomorrow.

Thanks

 

[omega015]

It doesn't sound like its that far away from the boiler so its probably not like its the last radiator to receive hot water. Turning the radiators off at one side with the TRV's is sufficient to stop the flow of water for this.

Yeah some lockshield caps actually can turn the valve instead of the dust cap style I showed, if this is open as you say then can you try fully closing it and giving it about a quarter turn open and having the TRV fully open and then you should hear the water going through it. Give it a while and measure the temperature on the radiator and the difference between the TRV and lockshield side. If the radiator still has a cold spot after say 15-20mins of running and the top is hot to touch, open the lockshield another quarter turn and give it time to warm up (hopefully).

Its hard to know which side is your flow/return but what we are trying to achieve is a small temp difference between both sides. If this doesn't solve the issue there could be sludge in the radiator that has settled which is stopping the flow of water heating that area up, which will require flushing out (can discuss more on that if needed afterwards).

 

[ipbr21054]

Hi,
This radiator is in a conservatory which when built then added to the system.
Radiator to boiler is 12ft etc.

So just screw down the thermostat valves.
When i turn heating on the inlet will get hot,then flow through the radiator, the out the outlet correct ?
if that is the case will all radiators have trv type ?
If not i just screw down the one the is cold when heating is switched on correct ?

If there is sludge in the radiator then like before,close both valves remove rad,hosepipe in one end then refit correct ?

This radiator is the only one which has a fitting for a hose pipe,this advise you of anything.

Sorry for all the questions but need this info before i start otherwise i will start & then be waiting for a reply if there is an issue etc.

many thanks.

 

[omega015]

Yeah just close the TRV on all radiators, you might not have one on the bathroom or hallway as its common for one to always be open as a bypass. Then fully open the TVR on the problem one and fully close the lockshield and quarter turn open. Switch on the heating and let it run for 20mins or so until nice and hot (preferably all the radiator), if still not fully hot, open lockshield some more. One of the radiator pipes will be hotter than the other to begin with, this side is the flow, eventually the other side should get just as hot (this is the return side).

If the cold spot is still there then yeah close off both sides, drain the water from the radiator and take off the wall and hosepipe the sludge out. Put the radiator back on and open the flow side valve and bleed the air out. You will need to top back up the pressure in the system and let any air out. Then open the return valve and check the pressure/air periodically for any trapped air.

Use this guide to help with taking off the radiator (leave the valves attached to the pipes. Undo the nuts connecting the valves to the radiator) http://www.judgeelectrical.co.uk/central-heating/radiators/how-to-remove-a-radiator.html just have plenty of old towels, pans, tubs, plastic sheet etc... when draining the radiator (before removing from the wall). Also tape up the radiator so the sludge and dirty water doesn't come out when taking it off the wall and staining your carpet etc...

The hose pipe fitting is just to help drain the system/radiator. Also not all radiators have TRV's, some might just have lockshield type valves on both sides, in which case just close one side of the radiator for the test.

EDIT: Follow the link above to take it off and be careful when tightening/untightening the nuts that you hold the lockshield valve with another set of pliers so that you don't bend the pipes (apply opposite pressure).

 

[ipbr21054]

Thanks for that, job for the weekend.
I forgot to mention that below the boiler and inline with the pipes is a red and black cylinder which is cleaned out once a year but nearly always clean.

 

[omega015]

something like this? This should help with catching some sludge but only the stuff that circulating the pipes.

 

[ipbr21054]

That's it

 

[ipbr21054]

Hi,
Ive locked off both valves,did have since 2 days ago anyway.
Drained this radiator then took it outside.
Hose pipe nice and powerfull in each hole BUT water coming out as clean as it was going in.

 

[HERTS P&D]

It needs to be balanced.

Andy

 

[ipbr21054]

OK
So i will refit the radiator back to the wall.
Do i then fill it up with water like normal THEN balance ?

 

[ipbr21054]

Radiator back on & topped up.
No leaks & boiler now at a steady constant pressure.

Without touching any radiators "YET" ive got on this trouble radiator the TRV fully open,5 as shown on dial.
The other end which is a Lockshield type fitting was turned off all the way then opened 1/4 turn.

Central heating set for 20 degrees & after say 40 minutes of it being on ive taken these readings with a pistol type heat gun.

TOP LEFT 36 TOP RIGHT 34

MIDDLE LEFT 29 MIDDLE RIGHT 32

BOTTOM LEFT 24 BOTTOM RIGHT 28

Outlet pipe with TRV 12
Inlet pipe with Lockshield 20

Just for your info before making any changes.
Will check again in say 1 hour

 

[ipbr21054]

Hi,
I have just looked again at this radiator.
Whilst every radiator in the house is hot to touch you can put your hand on this one for ages no problem.

TOP LEFT 31 TOP RIGHT 31

MIDDLE LEFT 30 MIDDLE RIGHT 28

BOTTOM LEFT 22 BOTTOM RIGHT 26

Outlet pipe with TRV 16
Inlet pipe with Lockshield 22


Read more: //www.diynot.com/diy/threads/radiator-warm-cold.474948/#ixzz4Vr7KH500

 

[ipbr21054]

HI,
All radiators off and now this trouble radiator has come hot.
All other radiators slowly turned on say 1 turn and now all hot

Thanks