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Siemens Building Technologies
Basic Documentation RVL471
CE1P2524E
HVAC Products
10 Function block "Space heating"
23.10.2002
•
The RVL471 is in setback mode:
The room temperature generated by the room model is determined according to the
following formula:
t
Room model temperature T
RM
[ °C ] = (T
Rw
-
T
AM
)
*
e
3
*
k
t
+ T
AM
25
22
D
1
8
t
1
T
Rw
T
RM
T
Rw
T
Rw
Progression of room temperature generated by the room model
where:
e
2.71828 (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 NORMAL room temperature
T
Rw
Setpoint of REDUCED room temperature
10.4.5
Optimum stop control
During the building's occupancy time, the RVL471 maintains the setpoint of NORMAL
heating. Towards 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 lie 0.5 °C below the setpoint of NORMAL heating
(optimum shutdown).
By entering 0 hours as the maximum optimum shutdown, optimum stop control can be
deactivated.
10.4.6 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 sensor, the actual value is simulated by the room model.
The duration is determined according to the following formula:
T
Rw
– T
AM
t [ h ] = 3
*
k
t
*
(
– ln
T
Rw
– T
AM
)
where:
ln
Natural logarithm
T
AM
Composite outside temperature
k
t
Building time constant in hours
T
Rw
Setpoint of NORMAL room temperature
t
Duration of quick setback
T
Rw
Setpoint of REDUCED room temperature