Upstair radiators heating up only half-way

[i3looM]

Hi folks, I'm hoping someone might be able to help. I've got an odd issue with 2 radiators upstairs that are only heating up from the bottom (halfway on the smaller radiator, 1/3rd of the way up the larger radiator). Where the water is in the rad, its very hot but I've bled every rad in the house and these but no air is coming out from them.

The boiler I have is a British gas 330+ High efficiency condensing system boiler and the pump is a Grundfos Multihead G (branded with British/Scottish gas). I have 5 rads downstairs and only the 2 upstairs as its a mono pitch house. The boiler/pump and associated kit was all renewed in Jan 2010 as part of a government scheme, the existing pipe system was not modified but Danfoss TRV's were fitted to all bar 1 rad. Under the boiler there is the expansion vessel and the pressure gauge on it has not changed at all since I've been monitoring the problem, the black arm stays at 0 whilst the red arm is always at 1.5 . There is a filling loop but it is not and never has been connected. I can't recall why the installer said its there. I believe the system must get its water from the tank in the upper attic.

I don't remember using these rads last year so I don't know if they have ever worked since the upgrade but they did with the old boiler. Does anyone have any suggestions what could be causing the condition?

Thanks

 

[secret squirrel]

The black arm is telling you when its cold the pressure is at 0, the red arm is telling you when cold the black hand should be near this. 1.5 bar, the problem is you have no pressure in the sytem.

Connect the filling loop should be obvious where it connects to (make sure everytning is off) gently fill to 1.5, bleed rads, making sure that the pressure is 1.5 WHEN COLD.

Make sure filling loop is then disconnected this should cure your problem

 

[SimonJohns]

You need to fill the system using the filling loop so that the black arm goes to 1 bar.

If your not confident with connecting up. Upload a pic of the filling loop and we should be able to talk you through it

 

[i3looM]

Thanks guys, I managed to get it sorted following your advice.
Rads are nice and warm once again.

 

[SimonJohns]

Have a nice warm Xmas