Fault Analysis & Specifications - A.O. Smith 710 ASME 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 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 1 Check whether the temperature setting is too high.
・The hot water is not
available when a
fixture is opened
1 Check the power supply
[1] Check the power supply from GFI to the PCB
(Refer to section12-2)
[2] Check the power supply line to the water heater
2 Fault of GFI
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 (10 A)
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 and/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 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.
710 / 710 ASME Service Manual
Diagnosis
35
CONFIDENTIAL
Ver. 1.00
Checkp
oint
A
A1
A2,A3
A1
F