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Siemens Building Technologies Basic Documentation RVD230 CE1P2383en
HVAC Products 14 Function block Valve actuator heat converter / primary controller 27.05.2004
14 Function block Valve actuator heat
converter / primary controller
14.1 Operating lines
Line Function, parameter Unit Factory setting Range
81 Running time actuator heat converter s 120 10…873
82 P-band of heat exchanger control K 35 1…100
83 Integral action time of heat exchanger control s 120 10…873
84 Setpoint boost heat converter K 10 0…50
85 Maximum limitation of flow temperature °C --- Variable…140
86 Minimum limitation of flow temperature °C --- 8…variable
87 External heat demand °C 60 0…100
88 Priority external heat demand 0 0 / 1
89 Heat demand input DC 0…10 V °C 100 5…130
14.2 Mode of operation
With plant types 2–x through 7–x, this function block controls the secondary flow tem-
perature of the heat converter according to the temperature acquired by flow sensor B1.
• With plant types 2–x and 3–x, it is the heat converter that supplies heat to the heating
circuit and the d.h.w. circuit via the common flow
• In the case of plant types 5–x, 6–x and 7–2, it is the heat converter that supplies heat
to all subsequent consumers via the precontrolled flow
With all types of plant, it is 2-port valve Y1 in the heat converter’s primary return that is
controlled.
This function block also provides minimum and maximum limitation of the flow tempera-
ture acquired with sensor B1.
With plant types 0–x, this function block is inactive; these types of plant are used exclu-
sively for d.h.w. heating.
14.3 Control process
If the actual flow temperature deviates from the setpoint, 2-port valve Y1 offsets the
deviation in a stepwise fashion. The controller drives an electric or electrohydraulic
actuator. The ideal running time of the actuator is 2…3 minutes.
The actuator’s running time, the P-band and the integral action time are to be set on
operating lines 81…83, depending on the type of plant. In addition, the heat converter’s
setpoint boost can be adjusted.
14.4 Maximum limitation of the flow temperature
The maximum limit value is to be set on operating line 85. The setting range for the
maximum limit value lies between the minimum limit value (setting on operating line 86)
and 140 °C.
At the limit value, the heating curve runs horizontally. This means that the flow tem-
perature setpoint cannot exceed the maximum value.
This function can be deactivated (entry of --- on operating line 85).
Maximum limitation is not a safety function; for that purpose, a thermostat, thermal
reset limit thermostat or similar must be used.
Note
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