Function Block Drt And Maximum Limitation Of The Return Temperature; Operating Lines; Maximum Limitation Of The Primary Return Temperature; General - Siemens RVD230 Basic Documentation

Note
Siemens Building Technologies
HVAC Products
27 Function block DRT and maximum
limitation of the return temperature
27.1

Operating lines

.
Line Function, parameter
171 Maximum limitation of primary return temperature heating circuits
172 Upper constant value, maximum limitation of the primary return
temperature
173 Slope, maximum limitation of the primary return temperature
174 Start of compensation (point of inflection), maximum limitation
of the primary return temperature
175 Lower constant value, maximum limitation of the primary return
temperature
176 Maximum setpoint of the return temperature with d.h.w. heat-
ing
177 Maximum limitation of the secondary return temperature,
reduction to the primary limit value
178 Integral action time of the primary return temperature limita-
tions
179 Limit value of the maximum limitation of the temperature
differential
180 Max. setpoint of the return temperature during d.h.w. heating at
the legionella setpoint
This function block contains all parameters of the district heat network. Since many
district heat utilities demand locking of the settings, they are arranged on the locking
functions level.
The following function blocks also belong to the locking function level. It includes all
operating lines from 171 through 196. This level can only be accessed with a code.
Also refer to subsection 32.1.6 "Setting levels and access rights".
In addition, locking on the hardware side is possible (operating line 196).
27.2 Maximum limitation of the primary return
temperature

27.2.1 General

The primary return temperature uses maximum limitation to
• ensure that too hot water will not be fed back to the district heat network
• minimize the pumping power of the district heat utility
• comply with the regulations of the utility (connection requirements)
Maximum limitation of the return temperature acquires the return temperature on the
primary side and throttles the primary 2-port valve if the limit value is exceeded.
Plant type Precontroller and heating circuit
Sensor
0–x –
1–x, 5–x B7
2–x, 3–x,
B7
6–x, 7–2
8–4 B7
Maximum limitation acts on both the heating circuit and the d.h.w. circuit; both consum-
ers have their own limit value.
Basic Documentation RVD230

27 Function block DRT and maximum limitation of the return temperature

Regulating unit
–
Y1
Y1
Y5
Unit Factory Range
setting
0 0 / 1
°C 70 Variable...140
7 0...40
°C 10 –50...+50
°C 50 0...variable
°C --- --- / 0...140
°C --- --- / 0...50
min 30 0...60
K --.- --.- / 0.5...50.0
°C --- --- / 0...140
D.h.w. circuit
Sensor Regulating unit
B72 Y5
B72 Y5
B7 Y1
B7 Y5
CE1P2383en
27.05.2004
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