T-D2-IN / T-D2-OS Service Manual
Ver. 1.00
24
CONFIDENTIAL
10-8. Flow adjustment valve
Unit Part #
#402
Takagi Part #
EK438
Checkpoint
J
Function
Controls water flow to properly control the output hot water temperature.
Failure events
1. Water leakage from valve.
2. The valve cannot modulate or make open/close positions.
Effects on the water heater
if flow adjustment valve
fails
1. Water leakage from failed valve can damage other water heater
components.
2. Temperature fluctuations in the hot water output.
3. Within an Easy-Link system, the “651” error code can occur.
Error codes when flow
adjustment valve fails
651 (only within Easy-Link systems)
Diagnostic
1. Visual inspection: connection/breakage of wires, motor drive locked due
to scale buildup, and/or water leakage.
2. Check voltages and resistance; proper range of values shown below.
Color/Number of wires
Black - Red
7 to 16 VDC and 0.09 to 0.2 k
Ω
The flow adjustment valve is assembled with the flow sensor.
IN
O UT
Flow
adjustment
valve
Flow sensor
Flow
adjustment
valve
Flow sensor
OU T
IN
+
-
-
+
1
3
2
O p en
(R e d )
３
Cl o se
(B l a c k )
１
M
N o .３
N o .2
No . １
Flow
adjustment
valve
>
P
P
E
-
G
F
<
1 - 7 / 8" ( 4 7m m )
3
-
3
/
8
"
(
8
4
.
4
m
m
)
2 - 5/ 8 " ( 6 7 .5 m m)
Flow adjustment valve
The flow adjustment
valve differs from one
in the T-K3-SP/OS.
