Hi all

I am a complete amateur trying to get my central heating going again.

I reattached an old radiator, bled it and all seemed fine then I noticed
that the downstairs radiators were all cold. Upstairs were lukwarm all of a
sudden.

I assumed an airlock but could not find air in any of the rads. Then I
looked in the attic and found that header tank was empty (and dry). Fixed
valve on stop cock and that seems to be ok now.

I ssumed system airlock. We don't seem to have a bleed valve on the system
in this house so I drained it down and refilled it bleeding all downstairs
and then upstairs.

Now when switched central heating on again, the water does not seem to flow
and boiler does not fully ignite (pilot only).

Can anyone detect anything screamingly obvious that I have neglected to do?

Pump is definitely working by the way.

Jules