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Siemens Building Technologies
HVAC Products
22
Function block Device functions
22.1
Operating lines
Line
Function, parameter
141
Actuator pulse lock
142
Frost protection for the plant
143
Flow alarm
144
Winter- / summertime changeover
145
Summer- / wintertime changeover
146
Pump kick
22.2
Actuator pulse lock
This function acts on all 3-position actuators controlled by the RVD240.
If, during a total period of time that equals 5 times the running time, an actuator has
received opening or closing pulses, additional closing pulses in the same direction will
be suppressed by the controller.
For safety reasons, the controller delivers a one-minute closing pulse in the appropriate
direction to the controller at 10-minute intervals.
A pulse in the opposite direction negates the pulse lock.
This function acts on all actuators used in the plant and is intended to reduce the wear
on the relay contacts and to extend the life of the actuators. It can be deactivated on
operating line 141 (entry of 0).
22.3
Frost protection for the plant
22.3.1 Principle
Frost protection for the plant protects both heating circuits against freeze-ups by acti-
vating the respective heating circuit pump. For this purpose, both the controller and the
heat source must be ready to operate (mains voltage present).
Frost protection for the plant is possible with or without outside sensor. The switching
differential is 1 K (fixed value).
Frost protection is always active, also
• when the control is switched off (standby )
• during quick setback
• during OFF periods by the ECO function
If required, frost protection for the plant can be deactivated (setting on operating line
142 = 0).
In addition to frost protection for the plant through activation of the heating circuit pump,
frost protection for the heating circuit flow is active.
22.3.2 Mode of operation with outside sensor
Frost protection for the plant operates in 2 stages:
1.
If the outside temperature falls below 1.5 °C, the heating circuit pump will be acti-
vated for 10 minutes at 6-hour intervals.
2.
If the outside temperature falls below –5 °C, the heating circuit pump will be acti-
vated and runs continuously.
When active, the respective frost protection stage will be switched off when the outside
temperature has exceeded the limit value by 1 K.
Basic documentation RVD240
22 Function block Device functions
Unit
Factory setting
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CE1P2384en
27.05.2004
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