Patent ID: 7810738

Claim:
A constant volume zoned heating and cooling air control system in a multiple zoned building comprising: each zone having an output for supplying conditioned air to said zone and an input for receiving return air from said zone; a constant volume central air handling unit for delivering temperature and humidity controlled air through a constant air volume supply air duct to all of said outputs; a return air duct for delivering return air from all of said zones to said central air handling unit; a heat exchanger for each zone for exchanging heat between air from said central air handling unit to said output and return air from each input to said return air duct; a free flow bypass for return air from the outlet of each zone to said return duct; and, at least one modulating fan upstream or downstream of said heat exchanger leading to said return duct for controlling temperature within each of said zones by controlling return air volume through the heat exchanger for each zone.