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The company preserves the right to change all specifications of the products and their accessories without prior notice
FORCED CIRCULATION BOILERS
RECOMMENDATIONS ON HEAT TRANSFER MEANS AND SAFETY AND
PROTECTION MEASURES DURING FILLING, OPERATION AND MAINTENANCE
OF THE SYSTEM
For the protection of the collectors’ circuit from frost, a solution of water and propylene glycol is used, which is non-toxic, at
a ratio suitable to provide frost protection down to -10° within the collector at an exterior temperature of -20°.
Once the system has been placed and until the installation is complete the glass panels of the collectors must remain
covered, until the boiler is filed with service water, so as to avoid the boiling of the filling liquid or the breakage of the glass.
The system must have the filling liquid replaced or topped up every 2 - 3 years. The filling must be accomplished with
a suitably diluted liquid. In addition, the circuit needs the provision of a differential thermostat with a sensor for the
protection of the circuit from frost which shall activate the circulation pump when the internal temperature r4°C.
Additionally, under no circumstances must the automatic filling valve be left open, as there is the danger that if the
collector bank has a small leak at some point which is leaking water, the automatic filling valve (if left open) will
continuously top up the system with water and so the ratio of the anti freeze liquid will be altered and the collectors
may break at the first sign of frost.
MAXIMUM OPERATING PRESSURE, PRESSURE DROP, MAXIMUM
AND MINIMUM INCLINATION ANGLE
The maximum operating pressure (taking into account the increase in pressure due to the water’s expansion) must
not exceed 400 kPa. The ideal water flow in a central system is 40 lt/m
2
h to 70 lt/m
2
h and the pressure drop per meter
of installed pipe (supply and return to the collectors) is 30mm of water. This is the data that is used for calculating the
dimensions of the circulation pump in each installation.
NOTE:
To the pressure drop of 30mm of water per meter of installed pipe one must add 10mm of water per square
meter of installed collector.
A basic factor in the optimum performance of the system is the correct selection of angle and orientation, in relation
to the installation site and the period during which we want the maximum yield. The solar system must be oriented so
that the collecting surface faces the geographical south for the northern hemisphere (and the geographical north for
the southern hemisphere), i.e. it should always face the equator. Any deviation in the orientation means a drop in the
system’s performance. If a deviation from the correct orientation cannot be avoided, then the system’s performance
must be corrected by increasing the collector surface, after study and evaluation of the particular circumstances. As
the solar radiation’s angle of attack changes over time and in relation to the system’s installation site, the collector’s
angle shall have to be equal to the site’s latitude ±5°. At this angle the maximum yield is achieved on an annual
basis. The system must not be shaded by trees, buildings or other obstacles so as to ensure 4 hours of unimpeded
exposure of the collector area during the midday hours.
