cold radiators

hi can any one help i have a combi system and i took the rads off to flush them out . they were filthy however after fitting them back and fill up rads upstairs are warm but downstairs are cold system worked fine before , just thought i would clean in good weather where did i go wrong cheers john

If your system was very dirty then your circulating pump may need encouraging to turn again.

Most makes have a means of manually turning the spindle, usually by removing a protective (and sealing) cap.

What make/model is your pump?

You may have unbalanced your system, you may have moved sludge from one place to another.

Fill the system without turning the boiler on but only up to a maximum of 1.2 Bar. Bleed each radiator in turn and refill to 1.0 Bar as appropriate.

Turn all lockshield valves closed and then open up by 2 turns. Turn all TRV's to 1/2 open, and fire up the combi.

You could before firing the boiler inject sludge remover into the system either via the filling loop or a radiator bleed valve this will break down any deposits that remain in the system, the system will then need to be flushed out after a period of 2 weeks and replaced with inhibitor.