Firstly, I would like to thank everyone who made suggestions on my recent question regarding putting up plasterboard over my existing kitchen ceiling.
I now have a new problem regarding SWMBO's cooker hood which is of the chimney type. We bought the hood yesterday and find that it requires carbon filters if it is not going to be vented to the outside and they cost GBP20.00 per set and require changing every 3 months (ouch!).
I can run a venting pipe (125mm) along the ceiling to the outside wall (boxed in of course) but the external grill would be just 40cm above the boiler flue pipe exit. I would use a grill with a Back Draft Shutter but is it going to be too close to the boiler flue and breach some regulation or other?