HEAT-EXCHANGE VENTILATION DEVICE

The present invention includes an air supply path 5 that is housed in a casing 2 and supplies outdoor air into a room, an exhaust path 6 that is housed in the casing and exhausts indoor air out of the room, an outdoor temperature sensor 18 that senses a temperature of outdoor air, an indoor temperature sensor 19 that senses a temperature of indoor air, a control device that controls volumes of air blow from a supply blower and an exhaust blower based on signals outputted from the outdoor temperature sensor and the indoor temperature sensor, a bypass passage 15 that is juxtaposed to an air supply passage or an exhaust passage to bypass a heat exchanger, and a damper 16 that switches between the air supply passage or the exhaust passage and a bypass passage. The control device executes control to perform a normal ventilation operation by switching the damper to the bypass passage and increase air volumes of the supply blower and the exhaust blower over air volumes in a heat-exchange ventilation operation that is performed before switching to the normal ventilation operation when a heat-exchange ventilation operation is performed, and determining that the temperature of the outdoor air is equal to or higher than a first threshold and a difference between the outdoor air temperature and the indoor air temperature is equal to or larger than a second threshold.