Radiators not heating..help!

[Lanloon]

Hey guys I have hudevad radiators installed. I have a long one in the Tv room that seems not to heat as well. The house is warm, temp is at 26.5 except for that room. It’s cold and if it heats up it becomes warmish. It was bled a few days but still the same. Any idea/tips of what it could be before I call them. TIA

26.5 is very warm.
What happens if you turn some other radiators down. Where is the thermostat? Could it be that it thinks it’s up to heat when it isn’t because of the combination of the above?

Have you played around with the actual thermostat on the radiator to check it hasn’t got stuck on low somehow?

26.5!
Blimey
Are you sat in your underwear?

turn off ALL the other rads at their knobs. What happens then, to the cool one?

Is it the same temperature all over?

Were all the radiators installed at the same time?

Is the cool one an "extra" that was fitted after the house was built, for example in an extension?

Typical causes of 'cold' radiators:

1. Air in the system - bleeding should resolve this, so probably not that.
2. Insufficient pressure in an unvented system. Have you checked the pressure?
3. Imbalanced radiators. When the new radiators were added, were all the radiators in the system rebalanced?
4. Dodgy Valves. I presume you have new valves on the new radiators, so this is unlikely to be a problem?
5. Insufficient boiler. When you added the new radiators, did you check the total heat output of all the radiators in your system vs. the heat output the boiler was capable of?

There are other causes, but probably worth ruling out these first..

It was bleed and pressure checked. We have been I. This his 3 years now so, I’m guessing they were all rebalanced as it was all new (including valves) but can I rebalance myself?

I have no idea about your 5th question..

*sorty it meant to say we have been in this house 3 years now

Has the long radiator in the TV room every worked satisfactorily?

Yes... but now I have 4 more not heating and the rest working fine.

I think it might be rebalancing but I have no idea how to do it...

I meant to say rebalanced 3 years ago.