Honeywell EXCEL 5000 User Manual page 170

ALPHABETIC REFERENCE
74-5577–33 (US)
EN2B-0184 GE51 R0518 (Europe)
The supply water temperature set TSup is calculated using te heating curve
equation. The room temperature setpoint is equal to the required TSet (next
occupied switch point) + P3 (no room temperature compensation).
TSup = HC (TSet + P3, TOat, P16 (curvature), P17(slope))
HC – meant heating curve equation
During preheat time, EOH3 generates the flow temperature setpoint according to the
heating curve, where the effective room temperature setpoint is increased by P3.
The preheat start point is a function of the outdoor air temperature.
t = P5/Tset * (Tset – TOat)
VV
At an outdoor air temperature of 0 °C, the preheat time starts 2 hours (P5) before
reaching the corresponding switch point in the Time Schedule.
If the outdoor air temperature (TOat) is equal to the room temperature setpoint
(TSet), the preheat point is not advanced.
The value of tVV is limited to a maximum of P2 (default is 48 hours).
min
tvv - pre-start time
P5
0
0
Tset room temp.setpoint
filtered outside air temperature
Example (at 10 °C):
Preheat time (P5) = 120 min
Minimum outdoor temperature for early setback (P4) = 0 °C
Setpoint (TSet) = 20 °C
Outdoor air temperature (TOat) = 10°C
t VV = (-120 min/ 20) * 10 + 120 min
t VV = 60 min
The following diagram illustrates this action:
optimum start
°C
room temperature
room temperature
day setpoint
– next switch point
night setpoint
172
EXCEL CARE CONTROL ICONS
°C
P3
(10 °C)
increase
P4
(0 °C)
pre-heat
time 0°C P5
5:00 8:00 time
calculated start point
start point time schedule