above a cooking surface many times the cooking surface is a range that includes a number of burners either gas or electric and also an oven the height of cooking surfaces usually is maintained close to three feet from the floor although this will vary for each installation and for each type of cooking surface employed a range hood will typically commence at about two feet above the cooking surface although it can certainly be higher than this with adjustments made for exhaust velocity and volumes the height of a range hood may then extend for another three feet or so and meet the ceiling dependent also on the existence or lack of bulkheads or as indicated above the range hood may terminate before it meets the ceiling in which case a chimney can be used to transition the gap in between fig5 7 8 and 9 show the blower and liner assembly with the mounting brackets installed and in fig9 as installed on the mounting board in particular the blower 14 includes the blower collector 60 the blower front 62 the blower side s 64 the blower housing 66 the blower transition 68 and the blower collector flange 70 the blower collector flange also shows the nuts 72 disposed at points along its length along the blower side s there are the pre drilled holes 74 lastly the blower duct 76.