A.O. Smith HYB-90N, Installation And Operating Manual

Page: 43 / 112

316888-001 Rev. 00 dRaFt Jun 28 245 www.hotwater.com 43
Fault
Code
Displayed
Description Cause
Lockout
type
Remedy
E15
Blower speed
abnormal.
Blower speed is 200RPM
below the target speed for
20 seconds.
Soft
Check the blower wire harness.
Change the blower.
Change the board. 1.
2.
3.
E16 Blower speed is 500RPM
above the target speed for 6
seconds.
E17 Machine starts or normal
combustion, but Blower
speed = 0 for last 3sec.
E18 Have Blower’s output signal
but the Blower speed = 0 for
last 400ms.
E19 Blower speed stuck > 3000
rpm
Soft
E20
Proportional
valve (PV) current
unusual.
Proportional valve Current <
Minimum.
Soft
Check the proportional gas valve
wire harness.
Change the board.
Change the gas valve assembly. 1.
2.
3.
E21 Proportional valve Current >
Maximum.
E22 Outlet
Temperature
Probe is Open
circuit. Outlet Temperature
is < minimum de
fi ned
temperature.
Soft
Check temperature probes wire
harness.
Replace themperature probe.
Change the board. 1.
2.
3.
E23 Outlet
Temperature
Probe is Short
circuit. Outlet Temperature
is > maximum de
fi ned
temperature.
E24 Inlet Temperature
Probe is Open
circuit. Inlet Temperature is
< minimum de
fi ned
temperature.
E25 Inlet Temperature
Probe is Short
circuit. Inlet Temperature
is > maximum de
fi ned
temperature.
E26 Tank Temperature
Probe is Open
circuit. Tank Temperature
is < minimum de
fi ned
temperature.
E27 Tank Temperature
Probe is Short
circuit. Tank Temperature
is > maximum de
fi ned
temperature.
E28 Ignition failure. After a failure to detect
the
fl ame during ignition,
the control will retry the
speci
fi ed number of times.
After the maximum failed
attempts, this fault is
declared. Soft
Check the igniter wire harness.
Check igniter 120Vac voltage
supply during the ignition time.
Check the ignition rod. If it looks
dirty clean it using isopropyl alcohol
and a clean cloth.
Check the high voltage wiring
connection between igniter and
igniter rod for proper contact. 1.
2.
3.
4.
E29 Outlet water
temperature too
low. Outlet water temperature <=
(setting temperature – 15°C)
for 60 seconds after
fl ame
detected.
Alert
Check the outlet temperature probe.
Change the board. 1.
2.
TABLE 5