A.O. Smith T-D2-OS User Manual

T-D2-IN / T-D2-OS Service Manual
Ver. 1.00
25
CONFIDENTIAL
10-9. Flow sensor
Unit Part # #402 Takagi Part # EK438 Checkpoint H2
Function
Detects and measures water flow rate using a spinning impeller and
magnetic pick-up.
Failure events
Unable to detect or measure any water flow rate.
Effects on the water heater
if flow sensor fails
Ignition sequence does not start (water heater will not initiate any
operation)
Error codes when flow
sensor fails
441 (only within Easy-Link systems)
Diagnostic
1. Visual inspection: connection/breakage of wires and/or debris on
impeller.
2. Check voltages: proper range of values shown below.
Color/Number of wires
Red - Black 4.0 to 5.5 VDC (Input)
White(85) -Black
1.0 to 4.0 VDC (pulse)
1,080 pulse/min (more than 18 Hz)
The flow sensor is assembled with the flow adjustment valve.
IN
OUT
Flow
adjustment
valve
Flowsensor
Flow
adjustment
valve
Flowsensor
OUT
IN
Flow sensor
>PPE-G F<
1-7/8" (47mm)
3-3/8" (84.4mm)
2-5/8" (67.5mm)
OUTPUT
VCC
GND
2
1
3
White
Black
Red
1 2 3
Flow sensor
The flow senor
differs from one in
the T
-
K3
-
SP/
OS.

A.O. Smith T-D2-OS Specifications

General

Brand	A.O. Smith
Model	T-D2-OS
Category	Water Heater
Language	English