CHECK THE PIPEWORK LEADING TO APPLIANCE FOR BLOCKAGES, DO YOU HAVE ANY IRON / STEEL PIPEWORK AS THIS CAN ALSO CAUSE YOU A PROBLEM GAT A CORGI ENGINEER TO DISONNECT THE PIPEWORK AND LET IT BLOW TO SEE IF THERES ANY IRON DUST IN THE PIPEWORK AND REMEMBER TO VENTILATE PROPERTY AND DONT OPERATE ANY SWITCHES OR NAKED FLAMES
STE, March 2009