we drained the sytem to do pipe alterations in bathroom, when finnished we turned all valves back on filling the system, when we turn on the boiler it ignites for about 10 seconds cuts out, the heating works but no hot water, we turn hot tap on, fire up the boiler, there are 5 red lights that come on one after another when it gets to 5 one the boiler makes huge banging noise followed by a big gulping sound of water dropping through the system even though we have released any airlocks via the rads, whilst the gas ignites we've had the hot tap open water becomes hot but then suddenly drops cold due to boiler cutting out, can you advise and save us from this nightmare, cheers. Daz

Darren, June 2007

No. On top of the pump plastic body there is a brass collar about 2" round. On top of that is a small plastic cap which should be left slightly undone(about 1or 2 turns).
It is an auto air vent to prevent the build up of air in the pump body and pipework.(sorry it took a while to respond, iv'e been working away)

T.h.s, June 2007

yes we too thought it was airlocking and if it is would there be any other alternatives to releasing the air as I've released the air from every where I can think of. Do you mean the large screw in the centre of the pump if so yes we loosened to release any air, Daz

Darren, June 2007

Sounds like it's airlocking. Have you opened the sealing cap on the auto air-vent on the pump?

T.h.s, June 2007