Hi. fitted new zone valve to systme,lost a bit of water but not much.pressurised to one bar .tuned on all ok then boiler stopped showing f25 .susspect air but dont know how to expel it .there is a valve on either flow or return next to boiler which some air and water has come out but problem persists(noisy too)HELP please

john kenyon, February 2010

thanks henry will try that and let u know

john kenyon, February 2010

try increasing pressure to 1.5 bar.

Henry, February 2010