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Siemens
Heating and D.h.w. Controller RVL481
CE1P2541en
Building Technologies
10 Function block "Space heating"
20.05.2008
10.4.7 Optimum
start
control
During the building's non-occupancy times, the RVL481 maintains the setpoint of
REDUCED heating. Toward the end of the non-occupancy time, optimization switches
the control to boost heating. This means that the selected boost will be added to the
room temperature setpoint. Optimization calculates the changeover time such that, at
the start of occupancy, the room temperature will have reached the setpoint of
NORMAL heating.
When the room temperature is simulated by the room model, that is, when using no
room temperature sensor, the forward shift in time is calculated as follows:
t = (T
Rw
– T
RM
) 3 × kt [min]
k
t
Building time constant in hours
t Forward
shift
T
Rw
Setpoint of NORMAL room temperature
T
RM
Room model temperature
Optimum start control with the room model takes place only if, previously, quick setback
took place.
Optimum start control can be deactivated by entering 0 hours as the maximum heating
up period.
10.4.8 Boost
heating
For boost heating, a room temperature setpoint boost can be set.
After changeover to the NORMAL temperature, the higher room temperature setpoint
applies, resulting in an appropriately higher flow temperature setpoint.
D.h.w. heating during boost heating does not affect the latter.
t
25
40
D
0
3
T
R
T
Rw
T
Rx
T
Rw
T
Rw
T
Rw
t Time
T
R
Room
temperature
T
Rw
Setpoint of NORMAL room temperature
T
Rw
Setpoint of REDUCED room temperature
TRx
Actual value of the room temperature
TRw
Room temperature setpoint
∆
TRw Boost of room temperature setpoint (with boost heating)
•
When using a room temperature sensor, boost heating is maintained until the room
temperature has reached the setpoint of NORMAL heating. Then, that setpoint will be
used again
•
When using no room temperature sensor, the room model calculates how long boost
heating will be maintained. The duration is determined according to the following for-
mula
t
1
= 2 × [h]
T
Rw
- T
RM1
T
Rw
- T
Rw
kt
20
×
The duration of the boost is limited to 2 hours.
Duration of boost: