Thanks for replying steve the gas.
No flame lift. its almost like worn brake pads on your car when it first kicks off for about 10 seconds then the rumble comes in for a short time and the pressure needle flickers, then dies off and settles down. Also something i didnt mention in my first post, they have just finished putting in a new gas main outside our house, and the rumble has been happening for only a few weeks but i thought it may just be a coincidence. Hope this helps.
