Fault Analysis & Specifications - A.O. Smith 110 Indoor 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
No display on
temperature remote
controller, even when
remote is turned on.
It takes long time to
get hot water at the
fixtures
The water is not hot
enough
The water is too hot
The hot water is not
available when a
fixture is opened
1 Check the power supply
[1] Check the power supply from Power ON-OFF switch to the PCB
(Refer to section12-2)
[2] Check the power supply line to the water heater
2 Fault of Power ON-OFF switch
Normal: 100 VAC between (white-black)
Normal: 100 VAC between (brown-brown)
3 Fault of transformer
[1] Disconnection / breakage of wires
Normal: 120 VAC between (white-black)
Normal: 100 VAC between (brown-brown)
4 Blown fuse at surge box (5A)
5 Fault of PCB
[1] No voltage at remote control terminal
Normal: 11 to 25 VDC between (white-black)
6 Disconnection/short-circuit/grounding of remote wires
Normal: 11 to 25 VDC between (white-black)
7 Fault of PCB of remote control
[1] Check for normal voltage at terminal
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 to receive hot water to fixtures quicker, you may want to consider
a hot water recirculation system.
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.
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
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.
110 Indoor / 110 Outdoor Service Manual
Diagnosis
35
CONFIDENTIAL
Ver. 1.01
Checkpoint
A
A1
A2,A3
A1
A2
F