T-M50 / T-M50 ASME Service manual
Ver. 1.05
28
CONFIDENTIAL
10-13. Freeze protection heaters
Unit Part #
#408
#425
#426
#441
AOS Part #
EKN86
EX001
EX002
EKN67
Checkpoint
L
Function
Prevents the heat exchanger, water valves, and water pipes within the water
heater from freezing. The heaters are but one of the freeze protection
devices in the water heater.
Failure event
Open circuit failure: ceramic heaters do not receive the voltage needed to
heat up.
Effects on the water
heater if heater fails
Ceramic heaters do not activate, allowing water contained in the heat
exchanger to freeze up, possibly causing the heat exchanger to burst.
Error codes when hears
fails
N/A
Diagnostic
1. Visual inspection: connection/breakage of wires and the condition of the
heaters.
2. Check: whether those are in the normal range as shown in the following
table.
Color/Number of wires
White -White
90 to 110 VAC (during freeze protection operation)
The
water
heater has four types of the heaters in it. All of them for protecting of the heat exchanger,
the water pipes, the water inlet and the water outlet.
Heater (#426 / EX002)
For the outlet (#441 / EKN67)
Outlet Heater
Heater 502 (#425 / EX001)
Pipe heater (#408 / EKN86)
