CE1P2522E / 30.03.2000
Basic Documentation RVL470
Siemens Building Technologies
22/68
Function block "Space heating"
Landis & Staefa Division
•
The RVL470 is not in quick setback mode:
The room temperature generated by the room model is identical to the actual room
temperature setpoint
•
The RVL470 is in setback mode:
The room temperature generated by the room model is determined according to the
following formula:
t
3
*
k
t
Room model temperature T
RM
[°C] = (T
Rw
– T
AM
)
*
e
Development of the room temperature as generated by the room model
25
22
D
1
8
t
1
T
Rw
T
RM
T
Rw
T
Rw
e
2.1828 (basis of natural logarithms)
k
t
Building time constant in hours
t
Time in hours
t
1
Quick setback
T
AM
Composite outside temperature
T
R
Room temperature
T
RM
Room model temperature
T
Rw
Setpoint of the normal room temperature
T
Rw
Setpoint of the reduced room temperature
8.4.5. Optimum stop control
During the building’s occupancy times, the RVL470 maintains the setpoint of NORMAL
heating. Toward the end of the occupancy time, the control switches to the REDUCED
setpoint. Optimization calculates the changeover time such that, at the end of occu-
pancy, the room temperature will be 0.5 °C below the setpoint of NORMAL heating (op-
timum shutdown).
By entering 0 hours as the maximum optimum shutdown, optimum stop control can be
deactivated.
8.4.6. Quick setback
When changing from the NORMAL temperature to a lower temperature level
(REDUCED or holidays / frost), the heating will be shut down. And it will remain shut
down until the setpoint of the lower temperature level is reached.
•
When using a room temperature sensor, the effective actual value of the room tem-
perature is taken into account
•
When using no room temperature sensor, the actual value is simulated by the room
model
The duration of quick setback is determined according to the following formula:
T
Rw
– T
AM
t [ h ] = 3
*
kt
*
( – ln ––––––––––– )
T
Rw
– T
AM
