Orion System SA Controller - Manual (Page 47)

SA Controller Technical Guide
Sequence of Operations
47
Supply Air Cutoffs
The Supply Air Temperature Cutoffs are designed to prevent extremely
High and Low Temperature Supply Air from entering the building.
High Supply Air Temperature Cutoff
High Supply Air Temperature Cutoff is initiated when the Supply Air
Temperature rises above the HI SAT Cutoff Setpoint. When this occurs,
Heating stages will be deactivated until the Supply Air Temperature falls
5°F below the HI SAT Cutoff Setpoint.
Low Supply Air Temperature Cutoff
Low Supply Air Temperature Cutoff is initiated when the Supply Air
Temperature falls below the LO SAT Cutoff Setpoint. If the SA Controller
is in WSE Operation, Vent Mode, or Heating Mode and the Supply Air
Temperature falls below the LO SAT Cutoff Setpoint for 10 minutes, it
is assumed a Mechanical Failure has occurred and all Heating will be
deactivated and the Supply Air Fan will shut off. If the SA Controller is in
the Cooling or Dehumidifi cation Mode and the Supply Air Temperature
falls below the LO SAT Cutoff Setpoint, the Cooling Signal or Cooling
Stages will immediately begin deactivating.
To restore normal operation, one of the following three things must occur:
1. The Supply Air Temperature rises above the LO SAT
Cutoff Setpoint by 5°F.
2. The SA Controller goes from Occupied to Unoccupied or
from Unoccupied to Occupied Mode.
3. The SA Controller’s power is cycled.
Supply Air Cutoffs