Service manual

T-M50 / T-M50 ASME Service manual

Ver. 1.05

CONFIDENTIAL

10-8. Flow sensor

Unit Part # #421 AOS Part # EKH33 Checkpoint H2

Function

Detects and measures water flow rate using a spinning impeller and magnetic

pick-up.

Failure event

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 the

flow sensor fails

441 (only within Easy-link and Multi-unit systems)

Diagnostic

1. Visual inspection: connection / breakage of wires and/or debris on impeller.

2. Check voltages: proper range of values shown below.

Red - Black 4.0 to 5.5 VDC (Input)

Color/Number of wires

White(+)-Black(GND)

1 to 4 VDC (pulse)

1,200 pulse / min (more than 20 Hz)

Water IN

Water OUT

7-7/7” (200mm)

7-1/8” (30mm)

2” (50mm)

Water IN

Red

White

Black