Unical MODULEX EXT 100, Installation And Servicing Instructions

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23
Instructions for the installer
3.12 - DETERMINATION OF PRIMARY BOILER PUMP OR BOILER SYSTEM PUMP
The size of the pumps must be determined by
installers or technical engineers according to
boiler data and system design.
The water side resistance curve of the boiler
is shown in the following diagram.
The pump is not an integral part of the boiler.
It is recommended to choose a pump with
the rate and delivery head at about 2/3 of its
characteristic heating curve.
The boiler pump must have a delivery head which can ensure the
water flow rate as shown in the diagram “Water pressure losses”.
The following table gives an indication of the pump’s flow rate
in function of the Ät of the primary circuit if the installation has
a mixing header.
NOTE: The use of a mi-
xing header fitted bet-
ween the boiler circuit
and the system circuit is
always advisable.
It becomes INDISPENSABLE if the
system requires flow rates superior
to the maximum permitted boiler
flow rates, which is to say lower
than 15K.
For a
∆
T 20 K, of a MODU-
LEX 250 boiler, the max.
water flow rate requested
is 10514 l/h.
From the graph of the
boiler’s pressure losses,
it can be determined that the pump
must be able to guarantee a delive-
ry head of at least
1,6 m/H
2
O
WATER FLOW l/h
Pressure Losses (m/H
2
O)
3.13 - BALLSTOP VALVES
The installation of ballstop gate valves, on the C.H. flow and
return connection, is recommended.
Doing so, in case of normal or extraordinary service, the boiler
can be drained without emptying the whole C.H. sistem.
WARNING!
IT IS NOT ALLOWED TO ISOLATE THE SA-
FETY DEVICES, as the safety valve and the
expansion vessel, FROM THE BOILER.