Hi there, and thanks for the reply. The interior photo is somewhat misleading, and the highlight it shows isn't daylight coming in through the roof. I've adjusted the photo so you can see it a bit more clearly, and put an arrow where the water drips down from. I'm keen to hear any recommendations re the heat resistant sealant ... Cheers, Kev.
Hi kev100 It looks like you have a twin wall flue outside which becomes a single skin flue inside the building. Try using plumbers flue silicone on the lower flue joints outside. If this doesn’t solve the problem you will have to investigate the single to twin wall junction and see if this has been properly joined. There is a remote possibility that the china mans hat on the top of the flue is not big enough. Regards S