Honeywell EXCEL 5000 User Manual page 153

EXCEL CARE CONTROL ICONS
EOH Operating Procedures
P18 Heating curve curvature
P19 Heating curve slope
EOH completes a total setback operation when the next switching point of the
optimal heating circuit occurs. In this case, the supply temperature setpoint is set to
32F (0C). At cool-down, EOH output overwrites the switching point in the Time
Program. If a further declination of the setback point occurs and is not optimally
reached, EOH continues to work under normal conditions. The cool-down phase
begins exactly as defined in the Time Program. During the cool-down phase, EOH
defines the supply temperature setpoint of the heating curve.
In the figure, the triangle notes refer to the following text:
1 Supply temperature from heating curve
2 Supply temperature 32F (0C)
3 Maximum of supply temperature during rapid preheating.
Heating Optimization WITHOUT Room Sensor
During preheat time, EOH works with a fixed prescribed increase (P6) of the room
temperature setpoint and varies the preheat point as a function of outdoor air
temperature. With a minimum outdoor air temperature of 32F, the preheat phase
begins 2 hours before reaching the corresponding switch point in the Time Program.
If the outdoor air temperature (X2) is equal to the room temperature setpoint (X3)
including the increase (P6), the preheat point is not advanced. If the outdoor air
temperature is between these two points, the advance (t VV ) of the preheat point is
calculated on the basis of the following linear equation:
t VV = (-P8/X3) * X2 + P8
In other words, preheat time advance is equal to the negative of preheat time
divided by room temperature setpoint and multiplied by outdoor air temperature plus
preheat time. The value of t VV is limited to a maximum of 48 hours.
155
ALPHABETIC REFERENCE
74-5577–33 (US)
EN2B-0184 GE51 R0518 (Europe)