That old chestnut

[scottiecb19]

Hi All,

I've got an upstairs radiator in my house that won't heat up. In an effort to sort the issue, I've tried all of the following, but none have resulted in the radiator getting hot:

- I've bled all of the radiators in the house to expel any air, especially in the cold rad - this rad is full of water;
- I've tried turning off all of the TRV's around the house, leaving the cold rad only open, and have tried the circulating pump on different speeds to see if I can clear any obstruction. The rad did not get warm;
- I've tried shutting the TRV on the cold rad and with the lockshield end open, I have drained approx. two litres of water from the bleed valve until warm water came out. I repeated this process, closing the lockshield and opening the TRV. Again, I drained about two litres of water until it ran warm. Clearly warm water from the system is able to reach the rad from both ends;
- I have tried balancing the system, turning all of the lockshields off on all of the other rads in the house, then just opening it a quarter of a turn. This has resulted in the cold rad getting slightly warm, but nowhere near warm enough to warm the room;

I'm at a loss what to do next. The water running from the rad is a light brown colour - I understand the correct colour considering it has fernox in the system. It is an 18 rad house, so quite a large system, but I cannot figure what else to try to get this one to work.

Any suggestions on this would be greatly appreciated!

 

[TeaTime]

When you turn the CH system on, does the flow pipe to the rad in question get hot?

Have you changed the TRV, or checked if the pin is stuck down?

 

[scottiecb19]

Sorry, should have mentioned that I've checked the TRV pin and it's free moving.

The feeder pipes are plastic and do not get hot, but the wall behind the rad is warm, presumably this is where it connects to the main system.

The rad is in one corner of the house, so I thought it was a problem with hot water flow to this area, but a rad directly below it downstairs gets hot, and I can feel up the wall that it is warm, going in the direction of the upstairs rad.

 

[andytw]

What make are the TRV's ? I have been replacing Myson heads where the head is broken and holds the pin down at all settings.
If in doubt, does the rad get hot with the TRV head removed completely ?

andytw

 

[scottiecb19]

I honestly haven't tried that yet - seems such a simple test doesn't it! Lol Think the TRV is a honeywell one, it's not the brand you mention I don't think.

Will try what you suggested when I get home. If that fixes it, there may be a resultant head-imprint in the nearest wall!!!

 

[andytw]

This is what I have had with the Myson heads... see the 'Faulty/Good' images

http://www.stevensonplumbing.co.uk/myson-trv2way-head.html

andytw

 

[scottiecb19]

From memory I'm sure the bottom of the TRV is white/cream plastic with a cross design - almost like your looking head on at a large phillips screwdriver. Nevertheless, I never thought to leave the TRV off to see if the rad heats up. The more I think about it, the more I hope this will solve it, as another thing I forgot to mention is that when the rad got warm, it got warm from the lockshield side not the TRV side.

Grrr, I don't want to be at work now, I want to go home to try out your suggestion!

 

[scottiecb19]

I'm 90% sure this is the TRV - http://www.crystalheating.co.uk/components/2.Drayton trv.jpg

 

[scottiecb19]

Sorry, I'm spamming my own post...

Thinking about it, if the TRV was stuck, then surely it wouldn't have been possible to have drained the 2 litres of water from the bleed valve when the lockshield was shut but the TRV 'open'. In fact, the water from the bleed valve flowed with slighter greater force when the TRV was open and the lockshield shut than the other way around!

 

[andytw]

It does sound as if water can flow in ether direction when you bleed water with each valve open in turn, so it does sound as though the TRV is open.

You have closed all other rads and this rad still does not get hot, but what warmth there is comes from the L/S end. If you have the valves you linked to then that is fine as they can go either end.

A long shot but wondering if the TRV washer has come loose so that you can bleed through it but when water is fed into the other end of the rad then it puts pressure on the loose washer and closes off the exit.

I have the same valves as you linked to. I did have one once with the rubber valve stuck down to it's seat, I had to give it a few hard clouts to free it up.

andytw

 

[PK Gas]

That type of valve in your link if you remove it youll see its got a white shaped disk inside.
while removed youll probably find when adjusting the temperature setting that the disc doesnt move up and down

 

[TeaTime]

Hang on, did you say that the flow pipe to the rad doesn't get hot, but the wall does? Doesn't sound like a trv problem then, more like a blockage or a pressure issue, especially if you don't think the TRV is broken.

 

[scottiecb19]

Thanks for the replies.

I tried removing the TRV head yesterday, unfortunately this has made no difference.

Would the pipework be blocked if I could pull warm water through when bleeding?

 

[andytw]

Yes, it is sounding like one of the valves is not working or the pipework is blocked. IMHO.

andytw

 

[xr4x4]

Did you turn off all the rads in the house?

Was the hot water off, I.e no water was flowing through the hot water cylinder?

Do you have a bypass! Is it passing?

What boiler is it? It may have an internal bypass.