28
McQuay OM 751
Description of Operation
Figure 16: Effective set point calculations
Table 15: Set point calculation examples
Examp
le A
Given
OccupancyMode = Occupied or BypassHeat/CoolMode = Heat
SpaceTempSetpoint = (not used)
SetpointOffset = (not used) = 0.0°F
SetpointShift = (not used) = 0.0°F
OHS = 69.8°F
Effective set point calculations
EffectiveSetpoint = OHS + Setpoint SetpointShift = 69.8 + 0.0 + 0.0 = 69.8°F
E
x
amp
le B
Given
OccupancyMode = Occupied or BypassHeat/CoolMode = Heat
SpaceTempSetpoint = 71.0°F
SetpointOffset = -1.0°F (occupant adjustment on remote wall sensor, or LUI)
SetpointShift = (not used) = 0.0°F
OCS = 73.4°F, OHS = 69.8F
Effective set point calculations
AbsoluteOffset = (OCS – OHS) / 2 =(73.4°F – 69.8°F) / 2 = 1.8°F
EffectiveSetpoint = SpaceTempSetpoint – Absolute Setpoint SetpointShift = 71.0 -
1.0 - 1.0 + 0.0 = 68.2°F
Set Point
Offset Input
(network input)
WallSensorType
Config. Value
1
+3°F/–3°F
Wall Sensor
Network Value
Space Temp
Set Point Input
(network input)
0
55°F/85°F
Wall Sensor
Network Value
Set Point
SetptOffset
Occupied Cooling Set Point (OCS)
Standby Cooling Set Point (SCS)
Unoccupied Cooling Set Point (UCS)
Occupied Heating Set Point (OHS)
Standby Heating Set Point (SHS)
Unoccupied Heating Set Point (UHS)
Occupied Cooling Set Point Shift (OCSS)
Standby Cooling Set Point Shift (SCSS)
Unoccupied Cooling Set Point Shift (UCSS)
Occupied Heating Set Point Shift (OCSS)
Standby Heating Set Point Shift (SHSS)
Unoccupied Heating Set Point Shift (UHSS)
SetptShift (network inputs)
Occupancy Temperature Setpoints
(network configuration variables)
Local User
Interface
+5°F/–5°F
AbsOffsetOccupied = Setpoint - (OCS + OHS)/2
AbsOffsetStandby = Setpoint - (SCS + SHS)/2
Occupied and Bypass Modes
EffectiveCoolSetpoint = OCS + AbsOffsetOc Setpt OCSS
EffectiveHeatSetpoint = OHS + AbsOffsetOc Setpt OHSS
Standby Mode
EffectiveCoolSetpoint = SCS + AbsOffsetS Setpt SCSS
EffectiveHeatSetpoint = SHS + AbsOffsetS Setpt SHSS
Unoccupied Mode
EffectiveCoolSetpoint = UCS + UCSS
EffectiveHeatSetpoint = UHS + UHSS
If both entering paths have
valid values, then the network
value has priority.
Effective Set Point Calculations for each Occupancy Mode
If both entering paths have
valid values, then the keypad/display value
has priority.