Installation instructions S-HR series page 8
As standard the unit is provided with a water filter in the
return pipe of the unit. With this, possible contamination
of the central heating water is prevented from ending up
in the unit. The unit is also provided with an internal
safety valve set at 3 bar. This is connected to the
discharge construction to the waste together with the
condensation discharge.
If all, or a large part of the radiators are provided with
thermostatic radiator valves it is advisable to use a
pressure difference control (by pass) in order to prevent
flow problems in the installation.
The unit is designed to be used on sealed
system only.
Additives in the installation water are only
permitted in consultation with STREBEL
LTD.
When using more than one unit in an installation please
refer to the cascade installation instructions.
4.2 Expansion tank
All STREBEL
S-HR-T units are provided with an
expansion tank on top of the calorifier. This expansion
tank is connected to the three-way valve and the
circulation pump. By this means the expansion water,
when functioning for the hot water supply, is prevented
from being shut off from the expansion tank when the
radiator thermostat valves are fully closed. A second
expansion tank in the installation is not a problem.
The STREBEL S-HR units are not equipped with an
expansion tank pipe. If a S-HR unit is combined with an
Comfort calorifier, the expansion tank connection is
included in the internal piping of the Comfort calorifier,
to which the expansion tank can be connected. If a
different calorifier is used then one has to take into
account that the expansion tank should be connected
between the three-way valve and the unit circulation
pump.
In connection with correct functioning of the
unit it is necessary for the expansion tank to
be connected to the expansion tank pipe of
the unit.
The expansion tank which is used should be geared to
the water content of the installation. The pre-pressure
depends on the installation height above the mounted
expansion tank.
external installation pump with low velocity header
figure 4
choice of expansion tank
table 4
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1
