Here are a few things to consider, from a Reliance water heater Installation Instructions and Use & Care Guide.
This water heater is designed to automatically shut-off in the event of the following:
- The pilot flame is extinguished for any reason.
- The water temperature exceeds 195°F (91°C).
- Excessive build up of dust on the base ring filter or flame arrestor. See Maintenance of your Water Heater Section.
- The ignition of flammable vapors.
A thermocouple is used to determine if a pilot flame is present, and will shut off the gas supply to the main burner and the pilot if the flame is absent. This unit is also equipped with a thermal switch, designed to shut off the gas supply in the event the water heater has been exposed to flammable vapors (e.g., spilled gasoline), poor combustion caused by a blocked vent or insufficient combustion air. If the thermal switch opens:
Check the flame-arrestor for signs of high temperature (blue or black discoloration). See Figure 29.
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If there are signs of high temperature, inspect your installation for any problems with venting, combustion air supply and for a flammable vapor event (see "Pilot Light Troubleshooting Flow Chart" section). Correct any issues prior to resetting the thermal switch. If you suspect a flammable vapor incident has occurred, do not use this appliance. Immediately call a qualified technician to inspect the appliance. Water heaters subjected to a flammable vapors ignition will require replacement of the entire water heater.
- Reset the thermal switch by depressing the small button in the center of the thermal switch. Follow the Lighting Instructions found on the front of your water heater
A high temperature limit switch or ECO (Energy Cut Off) in the tank is used to shut off the unit if the water temperature exceeds 195°F (91°C). The ECO is a single-use switch, which, if activated, requires complete replacement of the entire gas control valve/thermostat. If the ECO should activate, the water heater cannot be used until the gas control valve/thermostat is replaced by a qualified technician. Contact your local dealer for service information.
Also make sure you check and clean the base-ring filter.
External Inspection & Cleaning of the Base-Ring Filter
- At least annually check the base-ring filter (Figure 29)
for any dust or debris that may have accumulated on
the filter screen. NOTE: If the water heater is located
in an area that is subjected to lint and dirt, it may be
necessary to check the base-ring filter more frequently.
- Follow the Lighting Instructions to turn off the water
heater and allow it to cool for 10 minutes before
attempting to clean the base-ring filter.
- Use a vacuum cleaner with a hose attachment to
remove any dust or debris that may have accumulated
on the filter. NOTE: If unable to inspect or clean the
base-ring filter, follow the “Cleaning the Combustion
Chamber and Flame-arrestor” instructions.
- After the base-ring filter has been cleaned, follow
the Lighting Instructions to return the water heater to
The guide also has a pretty good troubleshooting section.
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Make sure the unit has plenty of combustion air. Often after a flood in the basement, folks tend to shuffle things around. If things are stacked too closely to the appliances, the combustion air to appliances can be restricted.