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All 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. Outdoor air and exhaust/relief dampers shall be capable of and configured to automatically shut off during preoccupancy building warm-up, cooldown, and setback, except when the supply of outdoor air reduces energy costs or when outdoor air must be supplied to meet code requirements.
Exceptions to
  1. Nonmotorized (gravity back draft) dampers are acceptable for exhaust and relief in buildings less than three stories in height and for outdoor air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 0, 1, 2, and 3. Nonmotorized dampers for outdoor air intakes must be protected from direct exposure to wind.
  2. Nonmotorized dampers are acceptable in systems with a design outdoor air intake or exhaust capacity of 300 cfm or less.
  3. Dampers are not required in ventilation or exhaust systems serving unconditioned spaces.
  4. Dampers are not required in exhaust systems serving Type 1 kitchen exhaust hoods.
  5. Dampers are not required in systems intended to operate continuously.
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