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.

Hi I am based in mumbai, India.My architect suggested me to use Haffele Stella/ Nuvola ceiling hood. Can any one help me with its reviews. Whether such ceiling hoods work in indian conditions of cooking.

Hello Sunitha, The length of the duct pipe depends on the suction power of the chimney. Usually it is not recommended to have it more than 10 feet. You may have the duct near the chimney after having a core-cutting hole made. Ensure that the external end of the duct is atleast 12 inches and sloped downward so that there is no issues with rain. Thanks, Nitin CORNERSTONE DESIGNS Bangalore.