Function Block Locking Functions; Operating Lines; Mode Of Operation; Maximum Limitation Of The Primary Return Temperature - Siemens RVD110 Basic Documentation

Siemens Building Technologies
HVAC Products
19

Function block Locking functions

19.1

Operating lines

Line Function, parameter
151 Max. limitation of primary return temperature, constant value
152 Max. limitation of primary return temperature, slope
153 Max. limitation of primary return temperature slope, start of
shifting limitation
154 Max. setpoint of return temperature with d.h.w. heating
155 Integral action time, primary return temperature limitations
156 Max. limitation of temperature differential
157 Max. setpoint of the return temperature during d.h.w. heating
at the legionella setpoint
161 Raising the reduced room temperature setpoint
162 Daily forced d.h.w. heating at the start of release period 1
163 Idle heat function
191 Locking on the hardware side
Settings --- and --.- mean: function is inactive
19.2

Mode of operation

This function block contains all district heat parameters. Since many district heating
utilities demand that the relevant settings be locked, the district heat parameters are
arranged on the "Locking functions" level. This level can only be accessed with a code.
In addition, it is possible to make a locking on the hardware side. For details, refer to
subsection 22.1.6 "Setting levels and access rights".
19.3 Maximum limitation of the primary return
temperature

19.3.1 General

The primary return temperature can be limited to a maximum value in order to
• prevent too hot water from being fed back to the district heating utility
• minimize the pumping power of the utility
• comply with the regulations of the district heating utility
Maximum limitation of the return temperature measures the return temperature on the
primary side with sensor B7 and throttles 2-port valve Y1 when the limit value is ex-
ceeded. This maximum limitation is influenced by both the heating circuit and the d.h.w.
circuit. Both consumers have their own limit value.
With plant types no. 2, 3, 7 and 8, the valid limit value is controlled by the heat demand
of the 2 consumers. If both the heating and the d.h.w. circuit call for heat, the higher of
the limit values is used.
Maximum limitation of the primary return temperature has priority over minimum limita-
tion of the heating circuit's flow temperature.
When the primary valve is fully closed, maximum limitation of the return temperature
will periodically be reset, because in that case, return temperature sensor B7 is located
in standing water. To ensure reliable measurements, the valve will be opened for 1
minute at 20-minute intervals. If, after that, the primary return temperature is still too
high, maximum limitation will become active again, closing the valve again.
For primary temperatures exceeding 130 °C, a Pt 500 temperature sensor can be used.
Basic Documentation RVD110, RVD130
19 Function block Locking functions
Unit Factory Range
setting
°C --- --- / 0...140
7 0...40
°C 10 –50...+50
°C --- --- / 0...140
Min 15 0...60
°C --.- --.- / 0,5...50
°C --- --- / 0...140
0 0...10
1 0 / 1
Min --- --- / 3...255
0 0 / 1
CE1P2381E
27.05.2004
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