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Controlling Ventilation Air Flows
Animation Series 1:
Controlling Ventilation Air Flows
- Desired Ventilation Flows
- Overcrowded Offices
- Air Handling Unit Contaminated
- Outdoor Air Damper Opening Reduced
- Exhaust Not Operating Properly
- Supply Air to Office Shut Off or Pinched Down
- Economizer Operating
- Contaminated Outdoor Air
Supply Air to Office Shut Off or Pinched Down
Mouse over the animated picture above to see messages which are referenced in more detail below.
Pressure relationships between rooms is designated at the bottom of each room (with a plus for positive and minus for negative pressure).
[SUPPLY AIR] Supply air to a given space may shut down for different reasons--a mechanical failure, an ill conceived renovation (e.g. a renovation splits an existing room but does not provide for supply and return to each room), or because of VAV pinch down. In a VAV system, the supply air may be reduced because of thermal neutrality (i.e. the room does not require conditioning), but the VAV box should be set with a MINIMUM STOP high enough to provide ADEQUATE OUTDOOR AIR even when demand for conditioning is low. Notice that contaminants in the space with diminished supply are not diluted but rather build up. Occupants with inadequate supply air may suffer both excess pollution exposure and thermal discomfort.