The outside air flows through a damper and mixes up with the recirculated air. the mixed air passes through a filter to remove dirt, dust and other impurities. the air now passes through a preheat coil in order to prevent the possible freezing of water and to control the evaporation of water in the humidifier. after that, the air is made to pass through a reheat coil to bring the air to the designed dry bulb temperature. now the conditioned air is supplied to the conditioned space by a fan. from the conditioned space, a part of the used air is exhausted to the atmosphere by the exhaust fan or ventilators.
The outside air is sucked and made to mix with the recirculated air, in order to make up for the loss of conditioned air through exhaust fan or ventilator from the conditioned space.
