Siemens RVD240 - Direct D.h.w. Heating Via Heat Exchanger

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Siemens Building Technologies Basic documentation RVD240 CE1P2384en
HVAC Products 22 Function block Device functions 27.05.2004
Flow alarm:
ERROR
t
T
V
wx
2524D05
t
A
t
A
t
A
t
1
t
2
y
t Time T
V
Flow temperature
t
1
Start of ERROR display w Setpoint
t
2
End of ERROR display x Actual value
t
A
Waiting time (set on operating line 143) Y Setpoint band (setpoint ± 1 K)
• At t
1
, an error message is triggered; during the period of time t
A
(set on operating line
143), the actual value stayed below the setpoint band y
• At t
2
, the error message reset; the actual value x has reached the setpoint band y
The flow alarm can be deactivated by entering --:-- .
When the flow alarm function is activated, any flow or differential temperature sensors
(if present) may not be used for display since their signals are used for evaluation.
22.4.2 Direct d.h.w. heating via heat exchanger
With plant types x–4, this function is required to detect faults on the primary valve and
primary actuator, faults that may pose a risk to the end-user. Hence, this function has
not been introduced to monitor the performance of d.h.w. control but to monitor the
temperature!
The function will be activated when the current d.h.w. setpoint is exceeded by 10 K for
a period of 20 seconds.
The flow alarm appears on the display as ERROR and, on operating line 50, with error
code 123.
When no circulating pump is present (setting 0 on operating line 54), relay Q3 will be
energized; it can thus be used to switch on a monitoring device, for example.
Flow alarm for overtemperature supervision:
ERROR
t
T
V
w
x
2383D05
t
B
t
1
t
2
t Time T
V
Flow temperature
t
1
Start of ERROR display w Setpoint
t
2
End of ERROR display x Actual value
t
B
Waiting time (20 s) "Forbidden” range
Caution
Overtemperature
supervision