How do conversi to natural gas

Code 11 is for no ignition.
Here is what I find:

Check that the gas is turned on at the water heater, gas meter, or cylinder.
Ensure gas type and pressure is correct.
Ensure gas line, meter, and/or regulator is sized properly.
Bleed all air from gas lines.
Verify dip switches are set properly.
Ensure appliance is properly grounded.
Disconnect EZConnect™ or MSA controls to isolate the problem.
Ensure igniter is operational.
Check igniter wiring harness for damage.
Check gas solenoid valves for open or short circuits.
Remove burner cover and ensure all burners are properly seated.
Remove burner plate and inspect burner surface for condensation or debris.

IF it has been working fine and now it isn't, I would suspect an ignitor problem.

Rheem water heaters should not be converted from propane to natural gas. The burners have been optimized for the rated gas and will not work as well after conversion. (Unlike ranges where the gas/air flow ratios can be adjusted when the burner orifices and regulator are swapped, the water heater doesn't have that option.)

I wish I had better news for you. I recommend you get a new water heater for the LNG service; it will be safer and more efficient.

Cindy Wells

Call Rheem
Generally the company does not support changing type of gas since propane burns much hotter and has more pressure than natural gas.
You need different gas control valve, and need cast iron burner and orifice than matches that specific gas control valve.
http://waterheatertimer.org/images/IMG_1826-LP-burner-450.jpg
http://waterheatertimer.org/Water-heater-manufacturers.html

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

no.
propane burns much hotter than natural gas, and has higher pressure
gas valve and burner and orifice must be changed to switch between natural gas and propane
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html
Most manufacturers do not support converting gas on heater.

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) Rheem does not post service manuals.
Call Rheem and ask why, since the other big manufacturers, AO Smith and Bradford White do post service manuals.

2) You need new propane gas control valve, and matching combustion parts to fit existing tank.
http://waterheatertimer.org/pdf/Rheem-Water-Heater-parts-catalog.pdf
http://waterheatertimer.org/images/IMG_1826-LP-burner-450.jpg

3) Rheem does not recommend changing gas type, especially from natural gas to LPG.
LPG is higher pressure, and burns much hotter and requires cast iron burner, unlike the lighter-weight metal used for Natural gas burner.
The manifold tube and thermocouple must match the gas control valve, and gas-type and have correct thread for propane.
The combustion chamber and heat transfer surface can also be heavier metal for propane heaters.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Probably the burner and parts need to be cleaned yearly as recommended in most gas water heater manuals. Both tank and tankless today recommend same.
Open following link for Bosch troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Contact Rheem/Paloma if plumber was unable to repair problem:
Open following links for Rheem tankless resources including Rheem chat and phone support:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://www.rheem.com/products/tankless_water_heaters/customer_support/

hi pete here ill try and help this could be 2 things check the sensor on the unit the outher one is a qustion has the gas company changed your meter latley and turned off you gas and not come back to light your poilet because this code also means not enough gas or wrong type of gas

clean the front filter and then clean the burner assembly