10
3.5
DRAIN BACK UNIT (DBU) INFORMATION - Fig. 6
Positioning
The DBU must be located within a height of 3 metres of the top of the Solar collectors, see Fig. 8. The pipework from the
collectors to the DBU must always fall by a minimum of 40 mm per metre and must be insulated with high temperature
pipe insulation.
Dimensions
The dimensions of the DBU and clearances required for servicing are shown in Fig. 6.
Water connections
The connections at the top and bottom of the DBU are shown in Fig. 6.
Alpha SolarSmart 150 - General Information
Notes: 1. Use copper pipe and compression fittings only on the pipework between the DBU and solar collectors.
2.
The tubing from the solar collectors must always slope down towards the drain back unit (at least 40 mm per metre).
3. There must not be any part of the tubing that will allow water to collect.
4.
DBU Pressure relief valve - complying with BS 6759 and set to operate at 6 bar. The discharge pipe must be
routed clear of the DBU and terminate in such a manner that it can be seen, but cannot cause injury to
persons or property.
Fig. 6
Serial number: on the
top of the housing
C
D
B
A
153
130
127
276
57
374
567
82
>300
>500
>100
>100
357
>100
278
131
154
126
DBU Connections
A Return from collector to DBU 22 mm
B Flow from DBU to collector
15 mm
C Flow from cylinder to DBU
15 mm
D Return from DBU to cylinder
15 mm
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