Function Block "3-Position Actuator For D.h.w; Operating Lines; Function; Flow Temperature Boost - Siemens RVL471 Basic Documentation

Siemens Building Technologies
HVAC Products
20 Function block "3-position actuator
for d.h.w."
With plant types x–2 and x–4, this function block provides 3-position control of d.h.w.
heating.

20.1 Operating lines

Line Function, parameter
132 Flow temperature boost mixing valve / heat exchanger
133 Actuator opening time
134 Actuator closing time
135 P-band of control (Xp)
136 Integral action time of control (Tn)

20.2 Function

The 3-position controller is used for d.h.w. control (plant types x–2 and x–4).
20.2.1

Flow temperature boost

• Plant type x–2 (mixing valve):
For the temperature demand to the primary controller / heat source, the value of oper-
ating line 132 is added to the setpoint of d.h.w. flow sensor B3.
• Plant type x–4 (heat exchanger):
For the temperature demand to the primary controller / heat source, the value of oper-
ating line 132 is added to the setpoint of d.h.w. flow sensor B3.
20.2.2 D.h.w temperature control
The control process depends on the type of plant:
• Plant type x-2: The control mode is PI; the flow temperature is controlled by the
modulating mixing valve
• Plant type x-4: The control mode is PID; the flow temperature is controlled by the
modulating 2-port valve
Owing to the I-part of PI control, there is no offset. The opening and closing times of the
actuator can be adjusted separately.

20.3 Pulse lock

If, during a period of time that equals 5 times the running time, the actuator has re-
ceived only closing pulses, additional closing pulses delivered by the controller will be
locked. This minimizes the strain on the actuator.
For safety reasons, the controller delivers a one-minute closing pulse at 10-minute
intervals.
An opening pulse negates the pulse lock.
Basic Documentation RVL471

20 Function block "3-position actuator for d.h.w."

Unit Factory Range
setting
°C 10 0...50
s 120 10...873
s 120 10...873
°C 32.0 1...100
s 120 10...873
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CE1P2524E
23.10.2002