I am having a conservatory built and I will have a glazed window (non-opening) near to my boiler's gas flue vent. I'm not sure of exact distance but currently it is 300mm from the centre of the vent to my kitchen window frame. The conservatory will be just outside the window therefore approx. 250mm. The top & other side of the vent is clear and is over the height of my neighbour's fence (i.e. not enclosed any further on any other side, just the one where my new conservatory will be). I have had two heating engineers to visit and they both seem to unsure of the current regulations which is worrying! Can anyone on here help?! I have looked into extending the flue upwards but they don't seem to do the correct vertical extension kit for my boiler. If anyone can help with this too I would be grateful. My boiler is a Potterton Suprima 30 (standard efficiency) installed in 1998.