Thermostat (Cold-Weather); Thermostat (Standard) - Dometic G6A-8E Service Manual

Water Heater
Component
EN
Diagnostic Question
Thermostat (Cold-Weather) (On Demand Models)
Does the E.C.O. trip repeatedly?

Thermostat (Standard)

Does the gas solenoid valve fail to open
and no spark is present?
Is the gas/electric combination model
not operating while using either gas or
electric power?
Is the water too hot or too cold?
• When the water is too hot:
• When the water is too cold:
Action Based On Status
Confirm the cold-weather thermostat is seated
tightly to the heat exchanger. If the cold-
weather thermostat is not touching the heat
exchanger, it will kick on but not kick back off
when the ambient temperature drops below
40 °F (4.5°C) and eventually it will trip the
E.C.O.
If the cold-weather thermostat is loose, tighten
the set screw.
Confirm continuity. If there is continuity
when the ambient temperature is above
40 °F (4.5°C), the cold-weather thermostat
is defective and will cause the burner to fire
without running water through the system.
Replace the cold-weather thermostat.
If yes, check for continuity across the terminals
at room temperature.
If there is no continuity, replace the
thermostat.
Test the temperature of the water in the tank.
Extract water through the P/T relief valve and
use a surface temperature thermometer (meat
thermometer) to read the temperature.
Confirm that the thermostat ends the heating
cycle at approximately 140 °F (60 °C) ±10 °F
(±5.5 °C) or approximately 155 °F (68 °C)
±10 °F (±5.5 °C) for EXT models.
• If the heating cycle ends close to theses
temperatures, the operation is normal.
• If the heating cycle does not end close
to these temperatures, confirm that the
thermostat is seated on the tank properly.
• If the thermostat is seated properly and
the water is still getting too hot, replace
the thermostat.
OD Model Only: Check the operation to
confirm the user is turning the hot-water tap
fully and slowly to introduce the cold water.
Confirm that the thermostat calls for heat
after a heating cycle when the temperature
reaches 120 °F (49 °C) ±10 °F (±5.5 °C) or
approximately 135 °F (57 °C) ±10 °F (±5.5 °C)
for EXT models.
• If the thermostat calls for heat close to these
temperatures, the operation is normal.
• If the thermostat does not call for heat
close to these temperatures, confirm that
the bypass kit is set properly.
• If the bypass kit is set properly and the
water is too cold, replace the thermostat.
OD Model Only: Check the operation to
confirm the user is turning the hot-water tap
fully and slowly to introduce the cold water.
Diagnostic Procedures
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