Control Of Mixing Valve; General; Load Control; Setpoint Boost Mixing Valve And System Pump - Siemens Synco 700 Series Basic Documentation

Load control

Note
Load reduction
Load increase
Building Technologies
HVAC Products
9.6

Control of mixing valve

9.6.1

General

The thermal output of mixing valve control can be reduced by functions of a higher
priority (e.g. limitation of the return temperature) or by functions of other plant (boiler,
DHW heating) via load control.
The following mixing valve settings are valid for both 3-position and DC 0...10 V actua-
tors.
Main menu > Commissioning > Settings > ... or
Main menu > Settings > Primary controller > Mixing circuit controller
Operating line
Actuator running time
P-band Xp
Integral action time Tn
Locking signal gain
[Tn] return temp limitation max
For more detailed information about mixing valve control and its settings, refer to
chapter 5 "General functions, fundamentals".
By using the locking signal gain, it is possible to predefine how intensely the primary
controller shall respond to load control signals.
9.6.2 Load control
The primary controller can be influenced by load control signals of a heat source.
A load reduction can be triggered by one of the following functions:
• Protective boiler startup
• Minimum limitation of the boiler return temperature
The primary controller does not respond to locking signals triggered by DHW heating.
Load increase can be brought about in the form of pump or mixing valve overrun. In
that case, it is only a maintenance of load.
9.7 Setpoint boost mixing valve and system
pump
Typically, a mixing valve operates with a setpoint boost, enabling it to compensate for
boiler temperature fluctuations.
With system pumps, this setpoint boost is not a basic requirement for compensating
boiler temperature variations. However, in the case of long pipe distances between
boiler and consumers, heat losses can occur, depending on the quality of pipe lagging,
so that setpoint boost can be desirable in these situations also.
Main menu > Commissioning > Settings > ... or
Main menu > Settings > Primary controller > Primary controller
Operating line
Setpoint boost
Boiler sequence controller RMK770
9 Precontrol
Range
1...600 s
1...100 K
0...600 s
0...200%
0...60 min
Range
0...50 K
Factory setting
150 s
50 K
60 s
100%
30 min
Factory setting
10 K
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CE1P3132en
23.04.2009