Hi, Please can anyone help me re ceiling mounted extractor hoods. I am building an extension and hate the look of all extractors but know I need to have one. I like this one: www.johnlewis.com/john-lewis-partners-jlhda918-ceiling-cooker-hood-white/p2915670, They seem to be made for over an island. Is there any reason anyone knows why I can't have this over the hob on a back wall, the wall is external so the ducting can go out there or onto the extension flat room. Thanks for any help and guidance.