Effectiveness is influenced by capacity of unit. If you are trying to mount a 270 cfm fan more than 30" above cooktop, then it may make noise but will do little to clear the air. If it is 1000 cfm, then it can be higher than 30". So the answer is "it depends". Most people don't mount them more than 36" above the cooktop unless it is a really high powered unit.

Sophie, Patricia you are right cleaning the crystals would be a hell of a job. Hence I would like to look at designs like the other pic I attached which is I believe from the e.ion range of Falmec. As I have mentioned before this is a second chimney. The primary chimney hood is above my gas job in the kitchen countertop and is the main and daily area for cooking. This is the secondary area which I plan to use for some quick heating, occasional stir fry etc. The pendant chimneys that I have come across in brands like Elica and Falmec do not require ducting. The filter needs to be changed every 6 months or more. With my kind of usage I am assuming I would need to change it even later. What I am looking for is different brands which have pendant chimneys. Right now I am only aware of Elica and Falmec. I know Siemens and Bosch don't have it. Siemens has 2 models which are like a flat rectangular panel to be attached to the ceiling or false ceiling. But the cost is same as the Falmec chimney. My only respite may be the cylindrical Isola chimney models from Faber or even Hafele which are ip within budget.

I would go with the second plan, more or less. Having a fridge right next to the wall seems like a bad idea to me, and I personally can't stand ranges/cooktops on islands--I like the hood venting straight outside. But I would want more countertop to the left of the fridge--when I take food out of the fridge I would want to plop it right onto the counter, and it looks like there's not enough room as it is.

Jt Kr, Either the technician is making a weird suggestion or you may have misunderstood his suggestion. If the Chimney is installed 360 mm away from the wall the entire hob unit projects out by 360 MM. It would technically make it difficult for any taller person to cook. As it will be brushing against their heads. The suction may be impacted. What he may be suggesting instead (please recheck) is that don't mount it on the wall rather some models can be installed on the ceiling. He may be referring to that installation on the beam. (Such models are called island hobs) If you have the floor plan and 2 D elevation measurements we can try recommending alternatives. Thanks Nitin Cornerstone Designs, Bangalore.