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Siemens
Basic Documentation RVP360
CE1P2546en
Building Technologies
9 Function block: Space heating
2017-07-24
2
5
22
D
1
8
t
1
T
Rw
T
RM
T
Rw
T
Rw
Progression of room temperature generated by the room model
e
2.71828 (basis of natural logarithms)
T
R
Room temperature
k
t
Building time constant in hours
T
RM
Room model temperature
t
Time in hours
T
Rw
Setpoint for NORMAL room temperature
t
1
Quick setback
T
Rw
Setpoint for REDUCED room temperature
T
AM
Composite outside temperature
9.4.7 Optimized switching off
During the building's occupancy time, the controller maintains the setpoint for
NORMAL heating. Toward the end of the occupancy time, the control system
switches to the setpoint for REDUCED heating. Optimization calculates the switch-
over point such that, when occupancy ends, the room temperature will lie 0.5 °C
below the setpoint for NORMAL heating (early shutdown).
Optimized switching off can be deactivated by entering 0 hours for maximum early
shutdown.
9.4.8 Quick
setback
When changing from the NORMAL temperature to a lower temperature level
(REDUCED or holidays/frost), the heating is shut down. It remains shut down until
the setpoint for the lower temperature level is reached.
With room sensor, the actual value of the room temperature is taken into
account
Without room sensor, the actual value is simulated by the room model.
The duration of quick setback is then calculated according to the following
formula:
T
Rw
-
T
AM
t [ h ] = 3
*
k
t
*
(
-
ln ———————— )
T
Rw
-
T
AM
where:
ln
Natural logarithm
k
t
Building time constant in hours
t
Duration of quick setback
T
AM
Composite outside temperature
T
Rw
Setpoint for NORMAL room temperature
T
Rw
Setpoint for REDUCED room temperature
