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Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
11. Fault Analysis & Specifications
Remarks:
1. Proper range of values of voltage & resistance shown below.
2. Please refer to the wiring diagram for checkpoint positions.
3. Remove power to the water heater when checking for continuity, disconnections, resistance values, etc.
Natural of Fault
Diagnosis
Check
point
• No display on the
controller, even when
remote is turned on.
1 Check the power supply
[1] Check the power supply from Power ON-OFF switch to the PCB
(Refer to section 12-2)
[2] Check the power supply line to the water heater
2 Fault of Power ON-OFF switch
Normal: 120 VAC between (white-black)
Normal: 120 VAC between (white-black)
A
A1
3 Blown fuse at surge box (5A)
A2
4 Fault of PCB
[1] No voltage at the controller
Normal: 11 to 25 VDC between (white-black)
F
L
5 Disconnection/short-circuit/grounding of the controller wires
Normal: 11 to 25 VDC between (white-black)
6 Fault of PCB of the controller
[1] Check for normal voltage at terminal
• It takes long time to
get hot water at the
fixtures
1 The time it takes to deliver hot water from the water heater to
fixtures depends on the length of piping between them. The longer
the distance or the bigger the pipes, the longer it will take to get hot
water.
2 If you need hot water to fixtures quicker, you may want to consider
a hot water recirculation system.
• The water is not hot
enough
1 Check cross pluming between cold water lines and hot water lines.
2 Check whether the gas supply pressure is enough.
3 Check whether the temperature setting is too low.
• The water is too hot
1 Check whether the temperature setting is too high.
• The hot water is
not available when a
fixture is opened
1 Make sure the unit has a 120 VAC / 60 Hz power supply.
2 If the remote controller is used, check whether the power button is
turned on.
3 Check that the filter on the cold water inlet is clean.
4 Check whether the hot water fixture is sufficiently open to draw at
least 0.5 GM through the water heater.
5 Check whether or not the unit is frozen.
6 Check if there is enough gas in the tank. (for propane units)