18
The dimensioning of the expan-
sion vessel in the collector cir-
cuit must be such that, even af-
ter an interruption to the power
supply of the circulation pump
in the collector circuit during
the time of maximum solar irra-
diation intensity, operation can
be automatically resumed once
the power supply is restored,
and once the liquid in the collec-
tor has condensed again.
If the heat transfer medium can
vaporise in conditions of stagna-
tion, the expansion vessel must
be installed in such a manner
that upon stagnation, fluid is
forced out of the collector, but
no steam.
Note
If it is possible for the heat trans-
fer medium to vaporise in condi-
tions of stagnation, this entails a
specific dimensioning rule!
In addition to the usual dimen-
sioning for closed space-heat-
ing systems (expansion of the
entire heat transfer medium),
the expansion vessel must be
able to compensate for a vol-
ume which corresponds to the
total volume of the heat transfer
medium in the collector group
and all connecting pipes be-
tween the collectors, plus an
additional 10%.
It must be ensured that damage
to the expansion vessel cannot
Intrinsically safe solar system
be caused by the hot heat trans-
fer medium. In particular, the
daily temperature cycle which
arises during normal system
operation must not cause the
hot heat transfer medium to
reach the expansion vessel.
The expansion vessel must be
installed in the cold section of
the collector circuit, i.e. in the
part of the collector circuit where
the heat transfer fluid flows from
the storage tank to the collector.
In cases of doubt, it is neces-
sary to install a suitable cooling
line, e.g. coiled pipe or cooling
vessel, in front of the expansion
vessel.
Automatic bleed valves
We do not recommend automatic bleed valves! If, however, there is
no alternative, automatic bleed valves must always be installed verti-
cally. It is only permissible to install automatic bleed valves or similar
systems if a tight-sealing manual shut-off valve (e.g. ball valve) is
situated immediately ahead of each one.
After automatic bleeding of the system, the tight-sealing shut-off
valve must be closed manually, and remain closed. Only fittings
which are suitably temperature-resistant and pressure-resistant may
be installed, see p. 20, 6 bar.
!
The expansion vessel con only
be connected to the AMK col-
lectra ag pumps group, if it is a
tank with an integrated smooth
bore heat exchanger, chiefly a
hot water generator. When fill-
ing the tank through a plate
heat exchanger, a tank for cool-
ing off must be installed before
the expansion vessel.
In solar circuits with more than
one reservoir tank the expan-
sion vessel connection must al-
ways be made to the reservoir
tank with the lowest medium
Connecting the expansion vessel
temperature. The connection is
to be made at the outlet side
of the smooth bore heat ex-
changer (return flow solar-side),
although before any motor
switching valves, motor globe
valves or pumps groups (in flow
direction).
Solar systems with AMK col-
lectra ag vacuum tube collec-
tors must be completely bled.
At the upper connection to a
plate heat exchanger a heat-re-
sistant manual deaerator must
be installed. Depending on the
type of connection to the cool-
ing-off tank for the expansion
vessel a deaerator may need to
Bleeding
be installed there also. Manual
deaerators should be included
directly at the connection of the
smooth bore heat exchanger to
the reservoir tank.
