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E 503.4.6.4.1 Shutoff Damper Controls
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Outdoor air intake and exhaust systems shall be equipped with motorized dampers that will automatically shut when the systems or spaces served are not in use. Ventilation outdoor air and exhaust or relief dampers shall be capable of and configured to automatically shut off during preoccupancy building warm-up, cooldown, and setback, except when ventilation reduces energy costs or when ventilation shall be supplied to comply with the code requirements.
- Backdraft gravity (nonmotorized) dampers shall be permitted for exhaust and relief in buildings less than three stories in height and for ventilation air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 0, 1, 2 and 3. Back-draft dampers for ventilation air intakes shall be protected from direct exposure to wind.
- Back-draft gravity (nonmotorized) dampers shall be permitted in systems with a design outdoor air intake or exhaust capacity of 300 ft3/min (0.142 m3/s) or less.
- Dampers shall not be required in ventilation or exhaust systems serving unconditioned spaces.
- Dampers shall not be required in exhaust systems serving Type 1 kitchen exhaust hoods. [ASHRAE 90.1:18.104.22.168.2]