Wilo Economy Notice De Montage Et De Mise En Service page 34

delivery manifold pipe. As an option, a unit for
protection against low water level (WMS) (11)
can be installed or retrofitted on the inlet manifold
pipe.
In the case of small to medium systems, the
control unit (2) is installed on the base frame by
means of a stand (10) and completely wired to
the electrical components of the system. The
present Installation and operating instructions
contain only a general description of the complete
system.
High-pressure multistage centrifugal pump (1):
Different types of high-pressure multistage cen-
trifugal pumps are installed in the DEA depending
on the application and the performance param-
eters required. The number of these pumps can
vary between 2 to 4 (pumps with integrated fre-
quency converter) or 2 to 6 (pumps without inte-
grated frequency converter). The attached
installation and operating instructions provide
information on the pumps.
Control unit (2):
Different switching and control units of different
types and different comfort levels can be supplied
and installed to activate and control the DEA. The
attached installation and operating instructions
provide information on the control unit installed in
this DEA.
Pressure sensor/diaphragm pressure vessel set
(Fig. 2a):
• Diaphragm pressure vessel (8)
• Pressure gauge (9)
• Pressure sensor (12)
• Electrical connection, pressure sensor (13)
• Draining/venting (14)
• Stop valve (15)
6.3 Function of pressure boosting system (DEA)
Wilo pressure boosting systems are equipped with
non-self-priming, high-pressure multistage cen-
trifugal pumps as standard. These are supplied
with water via the inlet manifold pipe. If self-
priming pumps are used, or generally in the case of
suction mode from lower-lying tanks, a separate,
vacuum-proof and pressure-proof suction line
with a foot valve has to be installed for each pump.
It should be positioned at a constant incline from
the tank to the system. The pumps increase the
pressure and pump the water to the consumer via
the delivery manifold pipe. To do this, they are
switched on and off or controlled depending on
the pressure. The pressure sensor continuously
measures the actual pressure value, converts it
into a current signal and transmits it to the control
unit at hand. Depending on demand and the type
of control system, the control unit switches the
pumps on, in or off or changes the speed of one or
more pumps until the set control parameters are
reached. (A more precise description of the con-
trol mode and the control process is given in the
Installation and operating instructions Wilo-DEA
installation and operating instructions for the
control unit.)
The total delivery volume of the system is distrib-
uted over several pumps. This has the big advan-
tage that the system output is adapted very
precisely to the actual demand and the pumps are
operated in the most favourable power range in
each case. This design delivers a high level of effi-
ciency and an economical energy consumption for
the system. The first pump that starts up is called
the base load pump. The remaining pumps needed
to reach the system operating point are called
peak load pump(s). If the system is configured to
supply potable water according to DIN 1988, one
pump must be designated as a standby pump,
i.e. at maximum extraction, one pump is always
decommissioned or on stand-by. To ensure that
all the pumps are used equally, the control unit
exchanges the pumps continuously, i.e. the order
of switching on and the allocation of the base
load/peak load or reserve pump functions change
regularly.
The diaphragm pressure vessel installed (total
content approx. 8 litres) performs a certain buffer
function on the pressure sensor and prevents
oscillation of the control system when switching
the system on and off. It also guarantees low
water extraction (e.g. for very small leaks) from
the storage volume at hand without switching on
the base load pump. This reduces the switching
frequency of the pumps and stabilises the operat-
ing status of the DEA.
CAUTION!
To protect the axial face seal or slide bearing, do
not allow the pumps to run dry. Dry run may
cause the pumps to leak!
Protection against low water level (WMS) (Fig. 4)
that monitors the supply pressure is provided as
an accessory for direct connection to the public
water mains. Its switching signal is processed by
the control unit. An installation point for this pur-
pose is provided as standard at the inlet manifold
pipe.
In the case of an indirect connection (system sep-
aration through non-pressurised break tank), a
level-dependent signal transducer, which is
inserted in the storage tank, is planned as a dry-
running protection device. If a Wilo break tank is
used, a float switch is already included in the
scope of delivery. For existing onsite tanks, you
will find various signal transmitters in the Wilo
range that can be retrofitted (e.g. float switch
WA65 or low-water warning electrodes with level
relay SK 277).
WARNING!
Materials that do not adversely affect the qual-
ity of the water must be used for potable water
systems!
6.4 Noise
As can be seen in point 1.2.1, DEA are supplied
with different types of pumps and a variable num-
ber of pumps. Consequently, the overall noise
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