A.O. Smith TWI 35-200 Installation, User And Service Manual page 78

Code and
description
XB2-XXXX
(lock out error)
Ignition error
Three unsuccessful
ignition attempts.
XAF-XXXX
(lock out error)
Control error
Hardware failure
XC9-XXXX
(lock out error)
Control error
Hardware failure
78
Cause
No gas
Air in the gas pipes.
Defect in the spark igniter circuit.
Defect in the ionisation circuit.
Supply voltage too low.
Bent flame probe is in contact with
metal surface.
Ceramic part, of the flame probe, is
broken or cracked.
Too many resets.
Disconnect the selection key.
Measure
- Make sure that the main gas supply
valve is open. If necessary, open the
valve.
- Make sure that the manual gas supply
valve, before the gas control valve, is
open. If necessary, open the valve.
- Make sure that the gas supply
pressure to the gas control valve is
correct, refer to Gas supply pressure.
- Bleed the air out of the gas pipe.
- Make sure that the gas supply
pressure to the gas control valve is
correct, refer to Gas supply pressure.
- Make sure that the spark igniter is
installed correctly.
- Make sure that the wiring of the spark
igniter is not damaged.
If necessary, replace the spark igniter.
- Make sure that the flame probe is
installed correctly.
- Make sure that the wiring of the flame
probe is not damaged.
- Measure the ionisation current. This
current must be a minimum of 60 μA.
If necessary, replace the wiring and/or
flame probe.
- Make sure that the supply voltage on
the controller is correct.
- If the supply voltage is below the
stated tolerance and the error
persists, contact your maintenance
and service engineer.
- Make sure that the flame probe is not
bend.
- If necessary, replace flame probe.
- Make sure that the ceramic part of the
flame probe is not broken or cracked
in the vicinity of the burner.
- If necessary, replace flame probe.
Turn off the power for 10 seconds.
- Make sure that the selection is
connected to J12.
- If necessary, replace the selection key.
Installation, Maintenance and Service part