In article ,
Tim Mitchell writes:
Glad you fixed it...

I have had to remove the flexible flue pipe on mine to fix a leak of
condensate at the bottom and it is not too bad to refit. You need to
refit the bottom first (with the top not fastened) and use some silicone
sealant round the bottom of it. When I had the leak problem, Keston
denied that there should be any sealant on it (and what was I doing
messing with it anyway, that was a job for the installer). However they
had put some on mine, it just hadn't been applied properly, hence the
leak.

The top joint of mine had some sealant on it when I disassembled it.
I didn't disassemble the bottom joint. Mine has the black flexible flue;
I believe some earlier C25's had a blue(?) flexible flue pipe which
Keston seemed to be replacing with a black one. Mine was black from
the beginning.

Having fitted the bottom you can stretch the pipe back up to the top
terminal and fit that.

Wee beasties can crawl down the flue pipe and end up in the burner /
condensate outlet. The flue pipe on mine is straight through the wall,
probably only about 12" long, so I can imagine things getting into the
burner and dying.

Same with mine, although I suspect being sucked in the air intake is
another possibility.

--
Andrew Gabriel