Cold radiators after system drain

[ultimatelightweight]

Hi forum.
I've recently drained my central heating system to fix a leak. Since the refil and rad bleed, I've got two rads that are cold. Bleeding them doesn't fix the issue as they run full but cold water.
Combi system.
Anyone have any ideas as to why this could be?

 

[buck51]

What procedure did you use to drain down?
What procedure did you use to refill and vent?

 

[ultimatelightweight]

Drain:
Hose pipe attached to drain run off on one if the offending rads. Opened the drain and allowed water to run. Opened a rad bleed valve on an upstairs rad until water ran slowly enough to replace a valve on another rad (still working and hot).

Refil:
Shut rad bleed valve, closed drain valve and refilled system from manual refil on boiler. Allowed system to heat up then bled each rad working low to high, near to far.

Followed a post on one of these forums but can't find it now!

Before I drained the rads worked and ran as hot as the others in the house. All worked well with no air in the system.

Have noticed after a long bleed that the feed pipe to the left of the rad (balance valve maybe?) gets warm but the rad and the water bleeding stays ice cold.

Help! It's -5 out and the two rads are kitchen and playroom for 10 month old twins! Can't afford a plumbers rates at this time of the year 😞.

 

[buck51]

you have an air lock some where, try closing all the reds that are working and see if that will shift the air lock.

next time fill and vent before you fire up the boiler.

 

[ultimatelightweight]

Thank you...thank you...thank you!
Turned all of the upstairs rads off and by the time is come downstairs both rads were filled with the left over hot water.
Boiler topped up and fired up now rads nicely warming...as are the others!

Thanks for your help.

 

[buck51]

Vent them all again. the air will finish up somewhere, then the system may need balancing.

By the way The Thanks button it top right