47
EN
Nonetheless, if cusps are necessary due to structural reasons,
relief valves must be mounted on both the delivery and return
sides.
80
120
0
120
20
40
60
° C 80
100
-
+
+
0
20
-
60
°C
40
-
+
100
-
+
SOLAR HEATING COLLECTOR
CUSP
TO SOLAR HEAT
EXCHANGER
SOLAR ADJUSTMENT
UNIT
Fig. 20
2.7.4
Solar expansion vessels
Expansion vessels must be adequately sized for containing ad-
ditional volumes of the water-anti-freeze liquid mixture, gener-
ated by thermal expansion and by steam, which could occur in
the collector. The membranes in the expansion vessel must be
able to withstand the maximum discharge pressure generated
by the safety valve (6 bar) and must withstand the water-an-
ti-freeze liquid (heat-transfer fluid) mixture.
Check that the expansion vessel pre-charge pressure is rough-
ly 0.3 bar less than the system’s cold charge pressure.
2.7.5
Thermostatic mixer
The thermostatic mixer must be installed on the output side
of the DHW calorifier, before the water reaches the withdrawal
point (to avoid scalding), as indicated in the enclosed system
diagram (see adjacent example).
To ensure correct mixing, the pressure of the hot water circuit
and the pressure of the cold water circuit must not differ ex-
cessively.
S3
S2
MIXER
Domestic
cold water
from the
mains
Domestic
hot water
To withdrawal
point mixed
To withdrawal
point
From the mains
Domestic hot
water expansion
vessel
Ball valve for
circuit balancing
Solar calorifier
Solar
circuit
Fig. 21
2.7.6
Connecting electrical devices
The control unit’s temperature sensors can be installed and
their respective cables laid by the plumber-installer; instead
the connection to the 220 V network and the powering up of the
solar circulator and motor-controlled pumps must be carried
out by a qualified electrician, as set out in the applicable regu-
lations, in accordance with the specific instructions accompa-
nying the system supplied.
To avoid malfunctions to the sensors, we suggest:
– Not to lay cables of the temperature sensors in a pipe where
a 220 V line has already been laid.
– Using shielded cables.
– Using a cable that can withstand high temperatures (e.g. sili-
cone cable) when extending the collectors’ sensor cable.
a
WARNING
We recommend connecting the support frame of the
solar collectors and the pipes to the house’s earthing
system.
