T-H2-DV/T-H2-OS Service Manual
Ver. 1.01
27
10-9. Secondary heat exchanger
Unit Part # 446 Takagi Part # EKH6X Checkpoint N/A
Function
Absorb latent heat from exhaust gas and transfer the water through the
secondary heat exchanger pipes, which can improve heat efficiency of the
unit by approximately 10%.
Failure event
1. Water leakage from the secondary heat exchanger.
2. Leaking exhaust gas.
Effects on the water
heater if the secondary
1. Water leakage from the secondary heat exchanger.
2. Exhaust gas leakage
N/A
Diagnostic
1. Visual inspection: soot deposits, cracks on the secondary heat exchanger
walls, and/or water leakage from the secondary heat exchanger.
2. In the event of abnormal sounds during combustion:
Inspect for soot buildup inside the secondary heat exchanger.
Color/Number of wires N/A
10-5/8" (269.4mm)
2-3/4" (70.8mm)
7-1/2" (189mm)