Siemens Building Technologies
HVAC Products
18.4.1 Charging boost
The charging boost for the d.h.w. setpoint can be set on operating line 116. This is the
difference between the heat demand to the heating medium (setpoint) and the setpoint
of the d.h.w. in the storage tank.
18.4.2 Flow temperature boost
The boost for the mixing valve or the heat exchanger in the d.h.w. circuit can be set on
operating line 118. In the case of direct d.h.w. heating via heat exchanger (plant types
x–4), the charging boost is also set on this operating line because the heat exchanger
is external.
18.5
Maximum setpoint of the d.h.w. temperature
On operating line 117, the maximum d.h.w. setpoint that can be set on operating line 4
is defined. Depending on the type of plant, the setting range is as follows:
Plant type
Minimum setting value
1–3, 1–9, 2–1,
Reduced setpoint (setting
2–2, 3–1, 4–9
on operating line 42)
1–4, 1–8, 2–6,
Reduced setpoint (setting
4–4, 4–8
on operating line 42)
In any case, the setting range is limited at a maximum of 100 °C.
18.6
D.h.w. charging with two storage tank
sensors
With the plant types using a d.h.w. storage tank, the storage tank temperature can be
acquired with one or 2 sensors (B31 and B32).
When using two storage tank sensors, the amount by which the setpoint of the colder
storage tank sensor is lower than that of the warmer sensor can be set on operating
line 119.
When 2 sensors are used, the switch-off criterion for d.h.w. charging is reached when
• the sensor with the higher temperature has attained the d.h.w. setpoint, and
• the sensor with the lower temperature has attained the reduced d.h.w. setpoint.
The "reduced setpoint" for the sensor with the lower temperature allows the secondary
return temperature to be kept low until the end of d.h.w. charging, in spite of mixing in
the stratification tank.
The switching differential of the d.h.w. temperature still applies.
18.7
Adjustable load limit
18.7.1 Adjustment to the time of year
To enable the controller to also provide stable d.h.w. temperature control when connec-
tion conditions vary (summer / winter operation) it must adjust the running time. This
adjustment is made with the current maximum stroke.
Basic documentation RVD240
18 Function block Valve actuator d.h.w.
Maximum setting value
Minimum selection from:
• Setting value on operating line 117
• Sum of setting values on operating
lines 116 and 176 (maximum limit
value of return temperature with
d.h.w. charging)
Setting value on operating line 117
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CE1P2384en
27.05.2004