I have a Keston boiler installed as specified with MUPVC flue about 18 months ago.
A 135deg bend has split, due (I suspect) to it's being stressed by a slightly wrong pipe length. So it drips condensate onto the floor.
You'll appreciate a speedy fix is much desired. Cutting out a section is no problem and avoids having to replace the Keston Flange if I replace the whole flue.
When I look up the Hunter website it says the fittings, (135swept bend and coupling) are not to be used on gas flues! Which might be why it failed.
Thanks in anticipation.