Error Heating Or Hot Water Supply Heater Failure - Toshiba HWS-802XWHM3-E Service Manual

[A12] Error Heating or Hot water supply heater failure
Restart
Operation starts under
10 TWI
Freeze prevention control is detected once
Heater backup operation
Heating: Booster heater
Hot water supply: Hot water cylinder heater
After 1 hour since heater operation
started, neither TWI
nor TTW 20°C is met
Water heat
exchanger board DPSW11-1,2
is ON
Backup heater or
hot water cylinder terminal
has 230ACV ( ± 23V)
Backup heater element
is conductive
Hot water
cylinder heater element
is conductive
TWI, TTW sensor
characteristics are
normal
Replace water heat
exchange control board
20°C
15°C
No
Yes
No
Yes
to backup heater or hot water
No
(Backup heater NG)
Yes
No
(Hot water cylinder heater NG)
Yes
No
(See characteristic table in page 101)
Yes
Power is connect
No
cylinder terminal
Yes
83
A12 abnormality detection
Set water heat board
DPSW11-1,2 to ON
Place electric wire for
backup heater
Place electric wire for
hot water cylinder
Set breaker for backup
heater to ON
Set breaker for hot water
cylinder to ON
or check indoor wiring
Replace booster heater
unit and safety valve
Replace hot water
cylinder heater
(Refer to hot water
cylinder guide)
Replace TWI or TTW
sensor