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With room sensor
Without room sensor
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Siemens Building Technologies
HVAC Products
When the limit value is reached, the heating circuit pump will be deactivated until the
room temperature has again dropped below the setpoint.
Maximum limitation of the room temperature is independent of the setting used for the
room influence.
12.9
Optimization
12.9.1 Definition and purpose
Operation of the heating system is optimized. According to EN 12098, optimization is
the "automatic shifting of the switch-on and switch-off points aimed at saving energy".
This means that:
• Switching on and heating up as well as switching off are controlled such that during
building occupancy times the required room temperature level will always be en-
sured
• The smallest possible amounts of energy will be used to achieve this objective
Optimization acts separately on each heating circuit; all settings are made separately
per heating circuit.
12.9.2 Fundamentals
It is possible to select or set:
• Operating line 74: Type of optimization
0 = according to the room model with no room temperature sensor
1 = with room temperature sensor or room unit
• Operating line 75: Maximum limit value for the heating up time
• Operating line 76: The maximum limit value for optimum shutdown
• Operating line 78: 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.
An outside sensor is always required.
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.
Without a room temperature sensor, the following functions can be provided:
• Optimum start control. Optimum start control operates with fixed values (no learning
process), based on the set maximum heating up time and the room model
• Quick setback. Quick setback operates with fixed values (no learning process),
based on the set maximum heating up time and the room model
Basic documentation RVD240
12 Function block Space heating
CE1P2384en
27.05.2004
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