"Julian" wrote:

Hello Julian

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

Could be a proper airlock. Hosepipe on the drain and a watchful eye on
the header tank can fix that...

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

....or, more likely, the boiler's locked itself since it overheated
when you ran without water. Take cover off and look for an obvious
reset button. Failing that, rifle drawers and then google for manuals.
Failing that, ask in here giving make and model.

--
Simon Avery, Dartmoor, UK
uk.d-i-y FAQ: http://www.diyfaq.org.uk/