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10 DIAGNOSTICS AND FAULT CODES
Alpha SolarSmart 100 - Diagnostics and Fault Codes
Codes 71, 72 and 80 will stop the solar system working:
The cause must be rectified before the system will operate.
When the cause has been rectified the system will start by itself.
Code 71
Collector sensor fault
Temperature of the collector is below -20°C or above 250°C.
Check the collector sensor: does it operate (check sensor resistance in table on next
page).
Sensor cable damaged or short circuited.
Sensor is faulty.
Code 72
Lower cylinder sensor fault
Sensor reading out of range.
Check the lower cylinder sensor: does it operate (check sensor resistance in table on
next page).
Sensor cable damaged or short circuited.
Sensor is faulty.
Code 80
Upper cylinder sensor fault
Sensor reading out of range.
Check the upper cylinder sensor: does it operate (check sensor resistance in Section
10.2).
Sensor cable damaged or short circuited.
Sensor is faulty.
Codes 74, 75 and 76 will lock the solar system:
The cause must be rectified before the system will operate. When the
cause has been rectified the system control can be reset by pressing the On/Off button for 3 seconds.
Code 74
No circulation in the collector
The collector and cylinder
temperature differential
remains greater than 40°C
for more than 15 minutes
Check water level in drain back unit.
Check the difference in height between the drain back unit pump and the top of the
collector. This can be a maximum of 4 metres.
Check that the pipework between the DBU and collector has the correct fall and length.
Check the collector sensor and the lower cylinder sensor, do they operate (check sensor
resistance in Section 10.3).
Check the collector tubes, are they blocked with dirt? Is the decline of the pipes within
the 40 mm per metre requirement.
Check the electrical connection and operation of the drain back unit pump and the
cylinder pump.
Code 75
Collector temperature too
high
The collector temperature
remains greater than 120°C
for more than 5 minutes
After 5 minutes the collector temperature is still too high (above 120°C) with the drain
back unit pump and cylinder pump operating.
Check the level of water in the drain back unit. Refer to filling procedure in Section 5.2.
Check the difference in height between the drain back unit pump and the top of the
collector. This can be a maximum of 4 metres.
Check the collector sensor and the lower cylinder sensor, do they operate (check sensor
resistance in Section 10.3).
Check the collector tubes, are they blocked with dirt? Is the decline of the pipes within
the 40 mm per metre requirement.
Check the electrical connection and operation of the drain back unit pump and the
cylinder pump.
10.1 FAULT CODES
The solar system is fully controlled by the electronic control unit on the cylinder. Fault codes will be displayed on the display
panel by means of a flashing fault code (71 to 80). See Fig. 23 and Section 5.4. The following codes can be displayed.
Code 76
Cylinder overheat fault
Cylinder temperature 85°C
or greater
The built in overheat thermostat function has activated.
Check cylinder pump function.
Check immersion heater setting (if fitted).
Check immersion heater thermostat is correctly set and switching off (approx. 60°C).
