central heating procedure

I believe I may have a problem with my central heating system. I flushed my system through today, not completely drained but let the system run whilst I opened the drain valve to flush through until fairly clean.

I then isolated the top up tank and allowed to drain down to the last inch, cleaned the tank out thoroughly and put a bottle of central heating preserve to clean out the sludge and refilled the tank. I opened the drain valve again to fill the system with the preserve solution and am now running the system but have found that my upstairs radiators are all hot but my downstairs ones are cold.

Now I know that convection means that hot water will always rise but is this normal or could I have a problem with my pump not supplying enough pressure. It is running but perhaps not pushing the fluid sufficiently around to reach the downstairs radiators. I also aim to balance the system before Winter but even unbalanced I would expect some heat downstairs, wouldn't I?

Don't be under the impression that your system is flushed because it is not. You will have an air-lock somewhwere you can spend hours trying to remove it but i often find that it clears itself within a few days it may also help to turn pump on & off

I spent weeks trying to clear an air lock when I extended radiators into the utility room and downstairs loo. There was a particularly awkwark bend in the run and so the air was stuck tight until I could run a significant amount of water through the system...not so easy with a combi!! All's ok now but keep venting air in all the rads and draining off at a low rad and it will clear even the most stubborn of air locks. Also try to do it before the weather turns nasty