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Siemens Building Technologies Basic documentation RVD240 CE1P2384en
HVAC Products 17 Function block Extra legionella functions 27.05.2004
17 Function block Extra legionella func-
tions
In d.h.w. systems with storage tanks, the legionella function ensures that legionella
viruses will not occur. This is accomplished by periodically raising the d.h.w. tempera-
ture in the storage tank.
17.1 Operating lines
Line Function, parameter Unit Factory
setting
Range
104 Legionella function 6 ---, 1…7, 1-7
105 Setpoint of legionella function °C 65 60…95
126 Time of legionella function hh:mm --:-- --:--,
00:00…23.50
127 Dwelling time at legionella setpoint min --- ---, 10…360
128 Circulating pump operation during legionella function 1 0 / 1
180 Maximum setpoint of return temperature with d.h.w. heating
at legionella setpoint °C ---
---,
0…140 °C
17.1.1 Legionella function
If and when the legionella function shall be activated is to be set on operating line104.
The legionella function can be started when the d.h.w. temperature is at the nominal
setpoint (button for d.h.w. heating is lit and no holidays are active). The function will be
deactivated when the frost level is reached.
The legionella function can be aborted by pressing the button for d.h.w. heating.
17.1.2 Setpoint
The legionella setpoint can be adjusted in the range from 60…95 °C (operating line
105). In the case of storage tanks with 2 sensors, the d.h.w. temperature must reach
the setpoint at both sensors.
17.1.3 Time
The legionella function is started at the set time. If no time has been set (operating line
126 =
--:--), the legionella function will be started with the first d.h.w. release at the nominal
setpoint.
If the legionella function cannot be performed at the set time because d.h.w. heating
has been deactivated (button for d.h.w. heating, holidays), it will be activated as soon
as d.h.w. heating is released again. In the case of d.h.w. heating with flow switch, the
legionella function will be activated at the set time, but the legionella viruses will only be
killed the next time d.h.w. is consumed.
17.1.4 Dwelling time
The legionella setpoint must be maintained for at least the set dwelling time.
If the lower storage tank temperature rises above the legionella setpoint minus 1 K, the
legionella function is considered completed and the dwelling has elapsed.
If the storage tank temperature falls by more than SD + 2 K (switching differential plus
2 K) below the legionella setpoint before the dwelling time has elapsed, the dwelling
time must again be completed.
If no dwelling time is set (operating line 127 =
---), the legionella function is completed
the moment the legionella setpoint is reached.
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