- 10 -
1-7 Scale Build Up Alarm
Summary
The temperature of residual hot water becoms higher as scale starts to build up inside the
heat exchanger. The extent of scale build up is judged by monitoring the temperature of re-
sidual hot water. “LC”, scale build up alarm, is indicated on the remote controller.
Flow chart (See page 35)
1) The set temperature by remote controller needs to be 120
F and over to activate the
alarm.
2) The stability of the temperature of outgoing hot water is detected by the thermistor of
the can body.
3) The temperature of residual hot water is detected by the thermistor of the can body
when hot water flow is stopped. The criterion for judging scale build up varies depending
on combustion capacity.
4) “LC” alarm and set temperature are indicated alternately on the remote controller.
Alarm specification
* Hot water supply is available even if “LC” is indicated on the remote controller.
* ”LC” alarm can be reset by turning the power switch off and on.
* No detection is possible in case remote controller is disconnected.
* ”LC” alarm is not memorized in the alarm history record.
Conditions for invalid detection
* The thermistor of the can body is broken or short-circuited.
* The alarm is in process.
* During forced combustion by the dip switch.
* The set temperature is under 120
F.
