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10-15. Hi-limit switch for exhaust
Part#
Function
Failure events
Effects on the water heater
if hi-limit switch for
exhaust fails
Error codes when hi-limit
switch for exhaust fails
Diagnostic
Color / Number of wires
When temperatures exceed 151 ˚F (66 ˚C), the reset button trips and switch goes to OFF mode.
ON mode : < 151 ˚F (66 ˚C) OFF mode: automatic restoration back to ON mode
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
• 319143-104 (EKH6G)
-Based on bi-metal thermal expansion.
-Detects excess temperature (more than 151˚F or 66˚C) of exhaust gas in
the exhaust chamber.
1. Unable to detect excess temperature of gas if switch fails "closed".
2. Continuous detection of excess temperatures (regardless of what the
actual temperature is) if switch fails "open".
1. Unable to shut down the water heater if the exhaust gas temperature in
the exhaust chamber exceeds 151˚F (66˚C).
2. The water heater is always shut down immediately after the ignition
process, and the "941" error code will display.
941 (Direct Vent Indoor models only)
1. Visual inspection: connection/breakage of wires.
2. Check voltages and resistance: proper range of values shown below.
White - White Less than 1.0 Ω
40
Page
Unit Part#
Checkpoint
3/4" ( 18 mm)
3/4" ( 17 mm)
3/4" (18.4 mm)
CONFIDENTIAL
Ver. 1.00
#472
K2
3-7/8" (100 mm)
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