Fault Analysis & Specifications - A.O. Smith T-H3J-DV Service Manual

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
1 Check the power supply
2 Fault of Power ON-OFF switch
• No display on the
controller, even when
3 Blown fuse at surge box (5A)
remote is turned on.
4 Fault of PCB
5 Disconnection/short-circuit/grounding of the controller wires
6 Fault of PCB of the controller
1 The time it takes to deliver hot water from the water heater to
• It takes long time to
get hot water at the
fixtures
2 If you need hot water to fixtures quicker, you may want to consider
1 Check cross pluming between cold water lines and hot water lines.
• The water is not hot
2 Check whether the gas supply pressure is enough.
enough
3 Check whether the temperature setting is too low.
• The water is too hot 1 Check whether the temperature setting is too high.
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
• The hot water is
3 Check that the filter on the cold water inlet is clean.
not available when a
4 Check whether the hot water fixture is sufficiently open to draw at
fixture is opened
5 Check whether or not the unit is frozen.
6 Check if there is enough gas in the tank. (for propane units)
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
[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
Normal: 120 VAC between (white-black)
Normal: 120 VAC between (white-black)
[1] No voltage at the controller
Normal: 11 to 25 VDC between (white-black)
Normal: 11 to 25 VDC between (white-black)
[1] Check for normal voltage at terminal
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.
a hot water recirculation system.
turned on.
least 0.5 GM through the water heater.
47
Diagnosis
Page
CONFIDENTIAL
Ver. 1.00
Check
point
A
A1
A2
F
L