Sounds like your gasvalve is failing to shut off properly.This boiler does not have a permanent pilot and is auto ignited,so if the flame should be going off but a small flame is staying on it is fairly dangerous and needs turning off,until you can get someone to look at it.Big problem though the boiler is virtually obsolete.
Tony S
February 2009
howtomendit.com for free repair help, information and advice.
