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6 Description and function
6.1 Pump description (fig. 1)
The Wilo-Stratos high efficiency pump (fig. 1) is a series of glandless pumps
with Electronic Commutated Motor (ECM) technology and built-in differential
pressure control.
On the motor housing there is in axial mounting form a control module (fig. 1,
pos. 1) which sets the pump's differential pressure to a set value that can be
varied within the control range. Depending on the control system involved, the
differential pressure is subject to different criteria. However, regardless of the
control system the pump constantly adapts to changing system power
requirements, as it is especially the case when using thermostatic valves or
mixers.
The main benefits of electronic control are:
• it saves energy while reducing operating costs,
• it reduces noise caused by the excess flow,
• it does not require pressure bypass valves.
This wet rotor pump is designed to have all rotating parts surrounded by the
liquid being pumped. The pump is maintenance free and requires no further
maintenance after the air bleeding procedure during the initial start-up
(no after start-up maintenance).
6.1.1 Differential-pressure control systems
The control systems which can be selected are:
• Δp-v: (Factory default setting) The electronics increase the pump's differential
pressure set point in a straight line between ½ Hs and Hs. The differential
pressure set point Hs increases or decreases in accordance with the required
flow rate (fig. 6).
• Δp-c: The electronics keep the differential pressure generated by the pump at
a constant differential pressure set point Hs over the entire operation range of
the pump (fig. 7).
• Δp-T: The electronics alter the nominal differential pressure set point
dependant on the fluid temperature measured. This control system can only be
adjusted with the IR module. There are two possible settings (fig. 8):
• Positive control: As the system temperature rises, the nominal differential
pressure set point is increased linearly between Hsmin and Hsmax. (setting on
IR module: Hs
Used e.g. with standard boilers with sliding flow temperature.
• Negative control: As the system temperature rises, the nominal differential
pressure set point is decreased linearly between Hsmin and Hsmax (setting on
IR module: Hs
Used e.g. with condensing boilers where a specific maxium return water
temperature must be maintained to achieve as much condensing as possible
to insure maxium boiler effeciency. To do this, the pump must be installed in
the system's return flow section.
Installation and operating instructions Wilo-Stratos
> Hs
).
max
min
< Hs
).
max
min
English
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