Operational Flow Chart - A.O. Smith T-M50 ASME Service Manual

9. Operational flow chart

Power supply ON
FAV&BV open
Operation SW ON
NO
Pre-check
NORMAL?
YES
B
Faucet opens
NO
Water Flow
Above 0.5GPM?
YES
BV modulates
Flow&temp
NO
Only one unit
should work?
YE S
FM speed NO
(Below
1,000rpm?)
YES
Both fan moter
start operation
Both fan motor
stop operation
FM speed NO
(Above
1,000rpm?) (20sec later)
YES
Flame rod NO
False flame
detects Below
DC0.15 A?
YES
Left Igniter ON
NO
Hi-limit
Normal?
YES
NO
OHCF
Normal?
YES
Left MV ON
Left SV2 ON
Left Igniter OFF
Left GPV ON
Flame rod
NO
detects Above
DC1.0 A? (5sec later)
YES
Burning lamp ON
Left Igniter OFF
(3sec later)
Proportional control
BTU
NO
change over
Left SV1 SV3 OFF
point?
YES
Left SV1 SV3 ON
NO
Below water
Left FAV CLOSE
heat capability?
YES
Below
NO
Max flow rate
restriction?
YES
Left FAV OPEN
Safety devices
YES
sensed
abnormal condition
NO
FAV ; Flow Adjustment Valve
B V ; Bypass Valve
F M ; Fan Motor
OHCF; Over Heat Cut-off Fuse
SV1 ; Solenoid Valve 1 (See the section 6)
SV2 ; Solenoid Valve 2 (See the section 6)
SV3 ; Solenoid Valve 3 (See the section 6)
False Dipswitch
settings
InTH failure
OuTH failure
MiTH failure
PCB failure
MV circuit failure
SV circuit failure
Fault of Bypass
function in Water
control Valve
Fault of Flow
adjustment function
in Water control
Valve
Bo th co m bu st i on se c t io n s
(r ig h t a nd l e ft ) w i l l
st ar t o p er at i on .
Left False detection
YES
NO
Reignition
Success?
M V ; Main gas Valve
GPV ; Gas Proportional Valve
InTH; Inlet thermistor
OuTH; Output thermistor
MiTH; Mixing thermistor
PCB ; Print Circuit board
(Computer board)
AFR ; Air Fuel Ratio rod
T-M50 / T-M50 ASME Service manual
C om p o ne nt s i n t hi s c h ar t
s wi t c h fr o m Le f t c om b us t i on
s ec t i on t o R ig h t c om b us t i on
s ec t i on .
B
031 blink
Primary combustion section
change from Left to Right
321 blink
YE S
311 blink
No error code
331 blink
in Right unit
701 blink
Y E S
510 blink
Error code
551 blink
in Left unit
661 blink
651 blink
*W h en
co d e a pp e ar s , bo t h
co m bu s ti o n s ec ti o ns
(r i gh t a n d/ o r le f t)
wi l l s to p o p er at i on .
Left Ignition failure
Left Flame blows up
391 blink 991 blink
Left Left
AFR rod
Abnormal
failure burning
311 blink 321 blink 331 blink
Left Left Left
OuTH OPEN InTH OPEN MiTH OPEN
or SHORT or SHORT or SHORT
(20sec later)
I n t h i s c h a r t ,
T h e p r im a r y u n i t i s
L e f t c om b u s t i o n s e c t i o n .
T h e s e co n d a r y u n i t i s
R i g h t co m b u s t i o n s e c t i o n .
13
CONFIDENTIAL
Remove cause
Opeartion lamp OFF
Operation stop
N O
NO
Flow sensor OFF
Faucet closes
*611 blink
th e " 6 11 " e rr o r
Fan motor
stop operation
721 blink
Left MV OFF
Left SV2 OFF
Left GPV OFF
111 blink
121 blink
Left SV1 SV3 OFF
121 blink 121 blink
Left
Left
OHCF melted Flame
(above 430 F)
blows out
*611 blink
Left
Fan motor
fault
Ver. 1.05