Hi guys new here please be gentle haha. Right I have drained down my vented central heating system to flush it out with a cleaner. I drained it out from the lowest point on my downstairs radiator opened all the bleed valves upstairs to drain the system down. After draining the system down I went through all the radiators one by one bleeding the air out, I noticed a weird noise from the boiler there was air in the system by the pump, I open the bleed valve on a magnetic filter on the return pipe to the boiler which released a lot of air but now the pump works but the boiler does not fire up. I was thinking from things I have read to put a hose directly to the drain valve on the boiler and push up the air ? into the header tank will this push all the air out of the system?. Cheers