Hello Phill, > and if correctly fitted will also dump lots > of water onto the fire..... I don't think it will - it will almost certainly have failed because there ain't no water above it! Even if here was water above the plug it would immediately flash into steam as it entered the firebox - as it does when a boiler is blown down. Regards, Barrie MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.