Wiring Diagram
305e/o, 305i, 505e/o, 505i
COLOR CODING
W :White
BK:Black
BR:Brown
R :Red
BL:Blue
Y :Yellow
P :Pink
O :Orange
G :Green
GY:Gray
1
3
BR
3
1
B
1
2
O
F
F
Dip SW1
3
8
7
6
5
4
F
5
W
W
B
1
BK
BK
MIN
MAX
MODULATING VALVE
CURRENT ADJUSTING
Gas pressure
F
4
W
W
W
P
W
W
OUTGOING WATER
THERMISTOR
HEAT EXCHANGER
THERMISTOR
Y
BR
O
R
W
BR
R
O
Y
W
BK
R
W
for REU-EZC
(Optional)
1
13
WATER FLOW
SENSOR
BK
F
2
Y
R
R
Y
BK
QS
BY-PASS FLOW
CONTROL DEVICE
Y
BK
R
FREEZE PROTECTION
OPTION
G
W
W
W
O
F
3
W
W
O
P
BL
R
BR
Y
GY
WATER FLOW
CONTROL DEVICE
R
BL
BR
Y
GY
G
R
AIR TEMPERATURE
THERMISTOR
R
BL BR
Y
INDOOR MODEL ONLY
COMBUSTION FAN
FM
R
BK
Y
W
E
1
W
4
1
Y
BK
R
BY-PASS SERVO MODEL ONLY
1
1
THERMAL FUSES
R
R
OVERHEAT
SWITCH
H
2
H
1
MODULATING
SOLENOID VALVE
POV
H
3
P
P
H
4
Y
FLAME ROD
H
5
SV1
H
7
H
6
SV0
BL
BK
SV2
BK
P
Y
BK
MAIN SOLENOID VALVE
SOLENOID VALVE 1
SOLENOID VALVE 2
F
6
Y
BR
BL
BK
P
P
(CN2)
Y
P
R
12
1
SOLENOID VALVE 3
H
8
BR
BK
SV3
GY
C
1
IG
GY
GY
IGNITER
GND
GY
SURGE
PROTECTOR
3
1
BR
BL
G/Y
D
2
W
BK
1
3
GND
FUSE
(3A)
BK
W
W
BL
BL
D
4
ANTI-FROST HEATER
AC120V
AC120V
HOT
NEUTRAL
HOT
NEUTRAL
GROUND
G/Y
D
1
GND
D
5
ANTI-FROST HEATER
BL
BL
D
3
FROST SENSING
SWITCH
W
BL
REMOTE CONTROLLER
SPARK
ELECTRODE
5
4
Spare Parts Only
Gas type
1
2
3
O
F
F
Dip SW2
6
A
C
D
E
F
G
H
F
1
G
1
(CN3)
(CN4)
(CN1)
(CN12)
(CN5)
(CN7)
(CN9)
5
3
R
R
F
7
(W) (W)
On-Demand Gas Tankless Water Heater Service Manual
17