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INSTALLATION – SOLAR COLLECTORS
27
PIPE LENGTHS
The solar hot and solar cold pipes between the solar storage tank and the solar collectors shall:
• be of DN15 hard drawn copper pipe.
• have a continuous fall from the solar collectors to the solar storage tank of a minimum 5° (1 in
10 grade).
• not exceed the maximum recommended lengths as specified in the table.
Maximum recommended total combined pipe length and number of 90° bends
1 or 2 Collectors 3 Collectors
Pipe Size
Pipe Length
90° Bends
Pipe Length
90° Bends
DN15 40 metres 20 30 metres 20
For each additional 90° bend, reduce the maximum total pipe length by 0.5 metres.
For each additional metre of pipe length, reduce the number of 90° bends by two.
Note: One 90° elbow is equal to two 90° bends.
Notes:
• It is important not to cross connect the solar cold and solar hot pipes to the incorrect connections.
• The solar cold pipe connects to the bottom of the solar collectors and the solar hot pipe connects to
the top of the solar collectors diagonally opposite to the solar cold pipe connection.
• The hot sensor connection is at the top of the solar collector, directly above the solar cold inlet
connection.
• Refer to “Warning: Plumber – Be Aware” on page 28.
It is essential for these requirements to be followed for the system to operate correctly and efficiently.
Solar pipe work which is oversized, or does not have the correct fall, or is too long can result in the
drain back system not operating effectively.
Maximum Height To Collectors
The solar collectors must be the highest point of the system. The maximum height of the solar
installation, from the base of the solar storage tank to the top of the solar collectors, is 9 m. The pump
will not circulate closed circuit fluid through heights greater than 9 m and solar gain will not be achieved.
For heights greater than 9 m, an auxiliary pump must be installed. Refer to “Auxiliary Pump” on
page 32.