Hood should be 6'' minimum larger than stove and at least 22'' deep if you cook. If you don't cook, don't sweat it at all.

Hello Abhinaya, Siemens & Bosch make are better ones.. Thanks Amit Cornerstone Designs Bangalore

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.

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.