What is eco failure - Rheem 50 Gallon FVR NATGAS Water Heater 6YR 22V50F1

I'm guessing about model. I Goggled Eco failure. For reheme this site and discussion may help. http://terrylove.com/forums/index.php?threads/ge-rheem-power-vent-eco-failure-code-gg50s06rvj.43646/
but since it's gas, and an expensive unit I'd call the installer or his service.

Question posted under Rheem water heater.
Model number and gas valve are unknown. Add a comment.

Following information applies to typical tank-type gas water heater, and does not apply to tankless water heaters, boilers, indirect heaters, solar water heaters, etc or for electric water heater.

Electric water heater ECO is located on upper thermostat.
Open top cover and ECO can be reset by pushing in red reset button,
Or ECO can be replaced by replacing thermostat. Add a comment.

Open following link to see typical tank-type gas water heater ECOs:
http://waterheatertimer.org/images/Intellivent-ECO-900.jpg
http://waterheatertimer.org/images/Typical-gas-valve-500.jpg

The ECO will trip at 180-200 degrees F.
This happens when the thermostat fails, then the burner stays on, and the water will continue heating.

With most water heaters, the ECO is one-time use device and the gas control valve is replaced.
Some water heaters have resettable ECO, but the overheating problem has to be solved.
Each water heater is different.
Contact Rheem or read manual for correct procedure.

If you have intellivent gas control valve, open following links for typical service manual:
http://waterheatertimer.org/How-to-adjust-temperature-on-water-heater.html#intelli
http://waterheatertimer.org/pdf/Intellivent-service-manual.pdf

More resources:
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

That is a power vent failure code.
Rheem is aware of this problem and are changing systems as we speak. Call your Rheem dealer and demand the updated system.

The ECO is designed to shut off the water heater in case of the water heater overheating. This is to prevent the water heater from exploding. I assume that you have a newer style residental water heater or a commerical boiler. The ECO is a fuseable link that is built into the control and located at the thermostat probe. If the water heater overheats then this link will melt cutting the circuit on the millivolt system(residential) or 24volt system(commercial boiler). If you look under the water heater control(where the temp adjustment is) there are usuall two wires that go from the control to the water heater. These are the ECO wires. Verify the wires have not been cut or damaged. If these wires are cut or damaged then the ECO circuit will be incomplete and you will get the ECO lockout failure. Also make sure that the flame lock-out switch is not tripped. It will be located at the burner compartment cover and have two wires going to it. Most have a little button in the center. These are to sense high heat and one might have tripped closing the circuit. You can push this little button to re-set the switch. If you feel a little "click" then the switch was probably tripped. If it does not have any button then it might be "self resetting". To test that switch use a continuity tester and the circuit should be closed. If these switches are working then the fusable link for the ECO is probably bad from the water heater temp getting too high or was defective and failed. This will require you to remove the water heater control valve and replace the fusable link. If you do not have experience with this I suggest you call a licensed plumber to make the repairs. If this repair is improperly done it could void the warranty on the water heater and/or cause property/personal damage or injury. There is a possiblilty that your water heater thermostat had failed causing the ECO to trip. If that is the case then the ECO safety did it's job.

That is a flame failure..there are many reason for this
be sure you have gas
there could be air in the gas line
flame sensor dirty

It sounds like your gas/air mixture needs to be adjusted. The flame should have just the slightest amount of white, at the very tip. The rest should be evenly blue. There is an air vent adjustment in the line to the burner, right after the gas input.

make sure your flue is clear,, and no suit is in the burner, also there are wires going to the ignitor make sure they are not touching after time for what ever reason they need to be seperated because they short out but doesn't cause any problem other then the unit not lighting

pilot will not ignite and eco failure code on high efficiency water heater, with electronic ignite

This water heater is equipped with a control which has a built inE.C.O. (Energy Cut-Off). The E.C.O. will shut the gas off,
should the outlet water temperature exceed 200 F. If the
E.C.O. has tripped, the entire gas control must be replaced.
For gas control replacement, contact your local gas utility, or a
qualified service technician. The replacement control must be
an identical model to the control which has been removed.

ECO "Energy Cut-Off"
http://www2.directenergy.com/builder/documents/Power_Vented_Rheem_FVIR_Tanks.pdf
Copy & Paste to search engine! If your not sure always call a Pro!