User Instructions for GECO GH21RA controller
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Page 34 Edition I
19.06.2013
When parameter
'
S49
'
= 1, note UW4 occurs, then the controller switches to safe mode and
the boiler operates without the
DHW/returning water temperature sensor.
Operating in safe mode without a working DHW sensor reduces the boiler temperature to
65° C and control of the DHW pump operates according to the setting of service parameter
S51. During safe mode, the DHW priority and Anti-legionella functions are not available. In
safe mode without working returning water sensor, the mixer pump is switched off until the
sensor is replaced.
Alarm 9
- Fuel feeder not turning/ damage to reed relay
The controller shows an alarm when no feeder rotation is detected, according to the sensor
value in the service parameters. The alarm is activated when the time between the pulses of
the reed relay is greater than 1.25 ·
'S19'
·
'S22'
[0.1s]. Safe mode operation continues until the
controller is turned off or power is cut. After this, the controller determines the damage to the
reed relay, and stores this as an alarm, so the operator must force safe mode again. In safe
mode, the controller will continue to operate ignoring the reed relay input, as if the sensor
had been turned off (S19)=0.