Siemens RVL471 - Process; Room Model Temperature

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Siemens Building Technologies Basic Documentation RVL471 CE1P2524E
HVAC Products 10 Function block "Space heating" 23.10.2002
• The maximum limit value for the heating-up time
• The maximum limit value for optimum shutdown
• Quick setback: Yes or no
To perform the optimization function, the controller makes use of the actual room tem-
perature – acquired by a room temperature sensor or room unit – or the room model.
Using a room sensor or room unit, it is possible to have optimum start and optimum
stop control.
To be able to optimally determine the switch-on and switch-off points, optimization
needs to "know" the building's heating up and cooling down characteristics, always as a
function of the prevailing outside temperature. For this purpose, optimization continually
acquires the room temperature and the respective outside temperature. It captures
these variables via the room temperature sensor and the outside sensor and continu-
ally adjusts the forward shift of the switching points. In this ways, optimization can also
detect changes made to the house or building and to take them into consideration.
The learning process always concentrates on the first heating period per day.
When no room temperature sensor is used, the room model only allows optimum start
control.
Optimization operates with fixed values (no learning process), based on the set maxi-
mum heating up time and the room model.
10.4.3 Process
HP
T
Rw
T
Rx
T
Rw
T
Rw
T
Rw
HP Heating program
T
R
Room temperature
tTime
t
1
Forward shift for early shutdown
t
2
Forward shift for the start of heating up
t
3
Quick setback
TRw Room temperature setpoint
T
Rw
Setpoint of NORMAL room temperature
T
Rw
Setpoint of REDUCED room temperature
∆TRw Boost of room temperature setpoint (with boost heating)
TRx Actual value of the room temperature
10.4.4 Room model temperature
To ascertain the room temperature generated by the room model, a distinction must be
made between 2 cases:
• The RVL471 is not in quick setback mode:
The room temperature generated by the room model is identical to the current room
temperature setpoint
With room sensor
Without room sensor