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Siemens Building Technologies
HVAC Products
12.5
Heating circuit control
Both heating circuits are controlled separately.
12.5.1 Weather-compensated control
Prerequisites for this type of control:
• Outside sensor connected
• No room unit connected or, if connected, room influence set to 0 (minimum)
The compensating variable for weather-compensated control is the composite outside
temperature. The assignment of the flow temperature setpoint to the compensating
variable is made via the set heating curve. The room temperature will not be taken into
consideration.
Main application of this type of control are plants or buildings in which
• several rooms are occupied at the same time
• none of the rooms is suited as a reference room for the room temperature
12.5.2 Room-compensated control
Prerequisites for this type of control:
• Room unit connected
• No outside sensor connected
If no outside sensor is connected, the setting on operating line 70 (room influence) is
inactive.
The compensating variable for room-compensated control is the deviation of the actual
room temperature from the setpoint from which the room influence is generated. In addi-
tion, an assumed outside temperature of 0 °C is included in the setpoint generation.
• When there is no room temperature deviation, the controller maintains the flow tem-
perature setpoint generated by the heating curve slope at an outside temperature of
0 °C
• Any room temperature deviation produces an instant parallel displacement of the set
heating curve. The correlation between the amount of the deviation and the extent of
the displacement is defined by the room influence. The room temperature is de-
pendent on the
deviation of the actual room temperature from the setpoint
−
set heating curve slope
−
−
set room authority
The purpose of the room influence is to exactly reach the required setpoint during the
control process and to maintain it.
This type of control operates as PI control. The I-part ensures that any deviations from
the room temperature setpoint will be compensated with no offset.
Main application of this type of control are plants or buildings where one of the rooms is
suited as a reference room for the room temperature.
12.5.3 Weather-compensated control with room influence
Prerequisites for this type of control:
• Outside sensor connected
• Room unit connected
• Room influence set in the range 1...20
Compensating variables for weather-compensated control with room influence are
• the composite outside temperature
• the setpoint / actual value deviation of the room temperature
The flow temperature setpoint is continuously shifted via the heating curve by the com-
posite outside temperature. In addition, any deviation of the room temperature pro-
Basic documentation RVD240
12 Function block Space heating
45/126
CE1P2384en
27.05.2004
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