Temperature And D.h.w. Switching Differential - Siemens RVL481 Basic Documentation

Siemens
Building Technologies
19.3 D.h.w. temperature and d.h.w. switching
differential
The kind of d.h.w. storage tank temperature acquisition must be entered on operating
line 126.
In plant types x–5 without solar heating, select setting 0, 1, 2 or 3 on operating line
126, although d.h.w. heating with electric immersion heater does not require either
sensor or thermostat.
The storage temperature can be acquired via
• 1 or 2 sensors
• 1 or 2 thermostats
• 1 or 2 sensors with solar function; this activates function "Solar d.h.w. charging".
If temperature sensors are used, the switch-on / off temperature for charging is deter-
mined as follows:
SD
BW
ON
OFF
T T = T
OFF BWw
ON
ON D.h.w. charging ON
OFF D.h.w charging OFF
SD Switching differential of d.h.w. charging
BW
T Switch-on temperature
ON
T Switch-off temperature
OFF
If the d.h.w. storage tank is equipped with thermostats, the switch-on / off temperature
is determined by the thermostats.
Determination of the switch-on temperature (start of d.h.w. charging):
Operating Measurement
line 126
0 1 sensor
1 2 sensors
2 1 thermostat
3 2 thermostats
4 1 sensor, solar
d.h.w. heating
5 2 sensors, solar
d.h.w. heating
Determination of the switch-off temperature (end of d.h.w. charging):
Operating line 126 Measurement
0 1 sensor
1 2 sensors
2 1 thermostat
3 2 thermostats
4 1 sensor, solar
d.h.w. heating
5 2 sensors, solar
d.h.w. heating
From the 2 tables above, it is obvious that when using 2 sensors, it is irrelevant which
of the 2 sensors is fitted at the top and which at the bottom of the d.h.w. storage tank.
Heating and D.h.w. Controller RVL481
19 Function block "D.h.w. storage tank"
T
BWx
T D.h.w temperature setpoint
BWw
T D.h.w. temperature
BWx
T Measured value d.h.w. storage tank sensor B31
BWx1
T Measured value d.h.w. storage tank sensor B32
BWx2
Switching criterion
T < (T – SD
BWx1 BWw
T < (T – SD
BWx1 BWw
Thermostat contact B31 closed
Both thermostat contacts B31 and B32 closed
T < (T – SD
BWx1 BWw
T < (T – SD
BWx1 BWw
Switching criterion
T > T
BWx1 BWw
T > T and T
BWx1 BWw
Thermostat contact B31 open
Both thermostat contacts B31 and B32 open
T > T
BWx1 BWw
T > T and T
BWx1 BWw
)
BW
) and T < (T – SD
BW BWx2 BWw
)
BW
) and T < (T – SD
BW BWx2 BWw
> T
BWx2 BWw
> T
BWx2 BWw
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CE1P2541en
20.05.2008
)
BW
)
BW