| 摘要 |
At the time of changing the discharge of air from a frontward discharge port (5) to an upper discharge port (4), the rotation speed of a convection type blower (18) is increased by delaying from the closure of the frontward discharge port (5) due to a damper (21). In a ventilation structure in which the direction of air oriented from the convection type blower (18) to the upward discharge port (4) is rectilinear and a flow path resistance is small, it is possible to reduce the noise generated. At the time of changing the discharge from the upward discharge port (4) to the front discharge port (5), the rotation speed of the convection type blower (18) is adjusted to the driving state of a combustion type blower (10), and thereafter the front discharge port (5) is opened by the damper (21).
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