Bought a second-hand gazco Marlborough gas stove (only used a few times) with the rear exit balanced flue but the instructions say the seals must be replaced if the flue is disturbed. There is a special sealant made by Corning, suitable for up t0 300 deg C but the design of the flue means the outer telescopic section is difficult to seal this way. Anyone know what sort of rubber O-ring might be suitable ?.
NB flue is 6 inches diam, and inner hot bit is 4 inches diam.