Cold radiator. Please please help

[Theo1226]

Last ditch attempt for help. Read others on the forum but none have my exact issues

I have a bad radiator in my house, the front room on the ground floor. I have a combi boiler, 5 Months old.

So far I have Change the TRV, changed the lock shield. Taken the radiator off and flushed it. Balanced the radiators. It’s still cold.

Today when changing the valves after bleeding the system then refilling, as I bled from top to bottom (nearest boiler) once the front room rad was fully bled it got hot, fast, like it should, I thought I had done it, went to the next rad and bled it, then the last one. Went back to the front room, and it had gone cold. So I turned the others downstairs off to see if that kicked it up again. It did not… So the radiator did work. Not for long mind, I’ve also ran X800 through for 12 hours, and drained directly from the bad rad trv.
If I turned all the other rads off then it heats up, fine. All of it. But as soon as another one is turned on, it starts going cold.. any ideas?!? I’ve drained and flushed the system like 7 times now. And I’m so done with this radiator!!

 

[Harry Bloomfield]

If I turned all the other rads off then it heats up, fine. All of it. But as soon as another one is turned on, it starts going cold.. any ideas?!? I’ve drained and flushed the system like 7 times now.

It needs properly balancing.

 

[Theo1226]

It’s been balanced

 

[terryplumb]

It’s been balanced

Who balanced the system ,and how ?

 

[Theo1226]

I did . First made note of what rads get hot in what order, then starting with the one that gets hottest first, Turned lockshield until it gets hot, moved on, I do the 4 on the top floor, then the front room but even fully open it doesn’t get hot. The only way it warms up is when all
Other rads are off, I’ve tried to slowly introduce other rads one by one, but it doesn’t work either.
Tried to leave the front room one till last to balance, but doesn’t work, tried to do the front room first, doesn’t work

 

[MickyP10]

Think the other rads need to be turned down. Turn hottest down a turn, then next hottest and so on. When you get close, eg your cold rad's warming up, adjust 1/2 to 1/4. This is an oversimplification of balancing, but it'll get you in the right direction.

 

[Theo1226]

Think the other rads need to be turned down. Turn hottest down a turn, then next hottest and so on. When you get close, eg your cold rad's warming up, adjust 1/2 to 1/4. This is an oversimplification of balancing, but it'll get you in the right direction.

It won’t heat up if other rads are on at all, it just doesn’t warm up,
I’ve tried it so I open the lockshield on the bad one fully, with it being the only radiator on at all, if I open a lockshield on any other radiator to the point it’s enough to warm up, it makes the bad one go cold.
The first 4 rads are open less than half a turn and they are lovely and hot. The ones down stairs a little more, I’ve experimented so much with different settings and different orders, the closest I came was all were on and working bar a towel rad in the bathroom, that lasted a day until the the front room just stopped getting hot

 

[MickyP10]

Hmmm, did it ever work okay?

 

[Theo1226]

Hmmm, did it ever work okay?

We’ve only lived here since April, so I’m not sure as first noticed it when the heating went on 2 Months ago, that’s how long it’s been breaking me!!
One plumber been out and said I need a new rad, but for example now, all the others are off, and the front room is lovely and warm, so it works. Just by itself haha, and another suggested a power flush that funnily enough he had a offer on for it

 

[MickyP10]

I'll give space to the experts. I'm thinking pump's not up to it, even boiler.

 

[Theo1226]

The boiler is only 5 months old. It went 6 weeks after we moved in

I'll give space to the experts. I'm thinking pump's not up to it, even boiler.

 

[terryplumb]

Is the problem radiator a vertical / designer type ,or a standard panel radiator ?
Given the fact that the problem rad heats fully when all others are closed off ,then there isn't anything wrong with it ,or it's valves. Close every other rads lockshield valve fully ,open the problem rads lockshield fully and turn on the central heating. Then go to any other rad and open it's lockshield a tiny fraction and wait 5 minutes to see if it heats up. If it doesn't open it a fraction more and wait again. Repeat this until a point is reached where the rad heats up.
Then move on to the next rad, repeating the process until all rads are heating up.
Tell us the results, particularly what effect this has on the problem rad.

 

[Theo1226]

Is the problem radiator a vertical / designer type ,or a standard panel radiator ?
Given the fact that the problem rad heats fully when all others are closed off ,then there isn't anything wrong with it ,or it's valves. Close every other rads lockshield valve fully ,open the problem rads lockshield fully and turn on the central heating. Then go to any other rad and open it's lockshield a tiny fraction and wait 5 minutes to see if it heats up. If it doesn't open it a fraction more and wait again. Repeat this until a point is reached where the rad heats up.
Then move on to the next rad, repeating the process until all rads are heating up.
Tell us the results, particularly what effect this has

It’s a double panel rad sorry forgot to specify, I will try this tomorrow, as not sure I’ve attempted this method yet, and will update tomorrow! Thanks for the reply! And I hope it works haha

 

[CountryFan]

What size is the pipework? Do you know if the boiler was range rated? What make and model of combi boiler?

 

[Harry Bloomfield]

Other rads are off, I’ve tried to slowly introduce other rads one by one, but it doesn’t work either.
Tried to leave the front room one till last to balance, but doesn’t work, tried to do the front room first, doesn’t work

It certainly reads, as if what you are not actually doing - is balancing them, rather you are turning them on and off, which is not balancing them at all. Balancing, is a slow process, of turning the valve on, a small fraction of a turn, then waiting, until the heat appears on one of the pipes, indicating some flow. A full turn from closed, is fully open, no restriction to the flow.