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1-6 Main Safety Devices
1. Water flow sensor (Boil-dry protection)
When the water flow sensor detects the flow rate set for starting ignition (ignition water
flow) or higher, the water heater starts operation.
Ignition water flow:
0.71 GPM (2.7 L/min.)
Extinction water flow:
0.58 GPM (2.2 L/min.)
2. Flame rod (Flame failure detection)
Electric signals are transmitted to the flame detection circuit to confirm the normal com-
bustion when the flame rod detects the rectification of normal combustion flame. There-
fore, if the combustion of the burners is not normal, the signals are not sent via the flame
rod. The gas control assemblies are closed without the signals and the error code "111"
or "121" is displayed on the remote controllers. (Normal with 0.8
A or higher)
3. Thermal fuse (Over-temperature protection system)
The thermal fuse is placed around the heat exchanger assembly. If the ambient tempera-
ture inside the water heater becomes extremely high, the fuse will melt down to break the
power circuit. In such a case, as no power is supplied to the gas control assemblies, the
gas supply is stopped and the combustion is stopped.
(The system is activated to blow the fuse at 363
F [184
C].)
4. Over heat switch (residual)
Even if the heat exchanger assembly is over heated by no-water combustion, every gas
path is closed to avoid risks. At this time, the error code "141" is displayed on the remote
controllers.
(The switch is provided with a auto-restoration function and turns OFF at 212
F [100
C].)
5. Fan revolution detection device (Hall IC)
The device detects the fan revolution speed to control the air supply necessary for normal
combustion. If the fan revolution is out of the preset standard range, the gas control as-
semblies are closed to stop the combustion before combustion failure occurs. In this case,
the error code "611" is displayed on the remote controllers.
6. Anti-freeze system (Frost sensing switch and heater)
To prevent freezing in the hot water supply circuit, anti-frost heaters are provided at major
points of water flow paths in the unit. The heaters are activated by the thermistors in the
unit.
The 4 heaters, one located on the front side of heat exchanger is 48W, the water supply
pipe is 16W, the connection of water inlet is 10W and the connection of hot water outlet is
10W. In order to keep the heat is the most vulnerable part of heat exchanger, the big
capacity 48W heater is mounted.
(The system turns ON at 37
F [3
C] and OFF at 55
F [13
C].)
