upstairs rads stone cold, downstairs red hot

plumb1_2

If you can drain it off again and refill from the mains.
Fit a hose to a drain off( if you have 1)
Connect the hose to a tap, open the drain off, and slowly open the cold tap. This will push any air out. be careful of leaks, best to connect pipe using a jubilee clip.

just another thought, is there a double check valve on the system

fannyadams

plumb1 wrote: »

If you can drain it off again and refill from the mains.
Fit a hose to a drain off( if you have 1)
Connect the hose to a tap, open the drain off, and slowly open the cold tap. This will push any air out. be careful of leaks, best to connect pipe using a jubilee clip.

we did this but, as you say, the pressure was a bit too much and we got a major leak after filling the downstairs rads so the top rads filled up from the F&E tank. and still the rads were cold upstairs but hot downstairs.

plumb1 wrote: »

just another thought, is there a double check valve on the system

i've not seen one, we've had a few boards up in the lads rooms but can't see any valves anywhere.

OK update.
took our bedroom rad off and flushed it with water - very black sludge came out of all of them and allowed the system to refill it , when we connected up the one in our room (with small bore) and the one in the bathroom they filled with hot water and were hot.
However, after leaving the heating on for an hour this rad was stone cold.
We've done the other rads (large bore) this way too, all had black sludgy stuff in them and they've all been flushed out thoroughly with water. however, when they were connected up they didn't get hot.

Am I now looking at having to get a powerflush?
if so how do I know who to trust on this -
NOTE I don't need a new boiler the damned thing is only 13 years old! and it won't take two pumps on the system.