If you have an unventilated kitchen, probably arranged in a passage for want of space, it is best to go in for an electric chimney that is powerful enough to exhaust out all the heat and kitchen smells... avoid the single exhaust systems and spend a little more and and get something that would really work instead of a piece that just looks like it is doing the work ... but isn’t really... Also the electric chimney is only really effective if it has an exhaust system instead of a recycle system. Try and have as few bends as possible in the exhaust pipe or the effectivness of the fan will be reduced.