Siemens RVD240 Basic Documentation page 37

Minimum and maximum
pump speed
Control of the heating
circuit pump
Siemens Building Technologies
HVAC Products
3 Q3 Intermediate circuit pump in connection with coil type storage
tanks
4 Q4
Storage tank charging pump in connection with stratification
storage tanks
In manual operation, the speed-controlled pump runs at the nominal speed.
The intermediate circuit pump used in connection with stratification storage tanks and
circulating pump K6 are not speed-controlled.
If the pulse-width-modulated output is assigned to a pump that is not used by the re-
spective plant type, it remains at 0 %.
• The minimum pump speed in % of the nominal speed is to be set on operating line
58. It should be as low as possible, but high enough to ensure that all consumers re-
ceive sufficient amounts of heat. The relay assigned to the pump is still connected in
parallel and can be used to fully deactivate the pump when not in use.
The setting range reaches from 0 to the value set on operating line 59
• The maximum pump speed in % of the nominal speed is to be set on operating
line 59.
If, due to the hydraulic layout, the maximum pump head must be reduced, this
should be done via a reduction of the maximum pump speed since this saves pump-
ing power.
If the pump may operate at nominal capacity, the maximum speed is to be main-
tained at 100 %.
The setting range reaches from the value set on operating line 58 to 100 %
The following illustration shows the control of the heating circuit pump. It shows the
pump speed and the flow and return temperatures as a function of the outside tempera-
ture.
In the upper outside temperature range (range 1; in the example T
pump speed is maintained at its minimum until the flow temperature – according to the
heating curve – would exceed the flow temperature setpoint T
In the lower outside temperature range (range 2; in the example T
flow temperature is then maintained at a constant level of T
continuously increased until the selected maximum speed is reached (operating point
A; T = –10 °C).
A
The heating output at operating point A is the same as the heating output that would
result at operating point B (flow temperature according to the heating curve, minimum
pump speed).
Basic documentation RVD240
11 Function block Plant configuration
= 20...–5 °C), the
A
(operating point C).
Vmax
= –5...–10 °C), the
A
. But the pump speed is
Vmax
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CE1P2384en
27.05.2004