Flow Sensor - A.O. Smith 510 Outdoor Service Manual

10-9. Flow sensor

Unit Part #
Function
Failure events
Effects on the water heater
if flow sensor fails
Error codes when flow
sensor fails
Diagnostic
Color/Number of wires
The flow sensor is assembled with the flow adjustment valve.
#402 AOS Part #
Detects and measures water flow rate using a spinning impeller and
magnetic pick-up.
Unable to detect or measure any water flow rate.
Ignition sequence does not start (water heater will not initiate any
operation)
1. Visual inspection: connection/breakage of wires and/or debris on
impeller.
2. Check voltages: proper range of values shown below.
Red - Black
White(85) -Black
Flow sensor
510 Indoor / 510 Outdoor Service Manual
319143-178
441 (only within Easy-Link systems)
4.0 to 5.5V DC (Input)
1.0 to 4.0V DC (pulse)
1,080 pulse/min (more than 18 Hz)
25
CONFIDENTIAL
Ver. 1.00
Checkpoint H2