(A) Except in the general commercial district, mechanical appurtenances, such as blowers, ventilating fans and air conditioning units, shall be placed not closer than 12 feet to any lot line.
(B) Any mechanical appurtenances, including elevator housings, stairways, tanks, heating, ventilation and air conditioning equipment, and other similar apparatus, located on the roof of any building shall comply with the following standards:
(1) Such apparatus shall be enclosed in a screening structure having walls constructed of material compatible in appearance with the main building to which it is attached.
(2) The apparatus and enclosure shall not exceed a height of ten feet above the surrounding roof surface, and shall not occupy greater than 10% of the total area of the roof of the building on which it is placed.