I unfortunately own a Omega 2000 Group tankless

http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#delime

Code 1L is scale build-up. Delime heat exchanger.

Gene

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Copy following link for troubleshoot resources, and possible manual for Rheem, Richmond, Paloma water heaters:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

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Call noritz
(866) 766-7489
http://www.noritz.com/contact-us/

Don't buy a tankless water heater.

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

Open following links for Bosch tankless resources, including some 1600 manuals, and contact information for Bosch:
http://waterheatertimer.org/pdf/Bosch-1600H-indoor.pdf
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
http://www.boschhotwater.com/BoschHotWatercomHome/GasProducts/tabid/331/Default.aspx

Tankless burner parts and combustion chamber need yearly cleaning, and tankless should be delimed each year.
http://waterheatertimer.org/pdf/Bosch_Overcoming_fluctuating_temps.pdf
http://waterheatertimer.org/pdf/Delime-tankless-water-heater.pdf

Best place to start troubleshoot is the manual.
For example manuals and key Rheem, Richmond, Paloma, Ruud troubleshooting links:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

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Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

1) The best place to find this information in your manual.
Typical Rheem manual in my files shows temperature is adjusted by pressing UP and DOWN temperature buttons on remote.

2) Manual says: Temperatures of up to 140°F
(60°C) for Light duty models and up to 180°F
(82°C) for Heavy Duty models can be
achieved with the MAIN (UMC-117) remote
control and a dip switch adjustment. Only
qualified service personnel should perform
this adjustment. Only factory authorized
remote control(s) should be used.

3) Typical manual shows information on page 22-23. Search pdf for 'temp'
http://waterheatertimer.org/pdf/Rheem-RTG74IndoorOutdoor_owners.pdf

4) This information squares with what I heard before that trained service technician is needed to adjust water temperature.
I think Rheem does this since tankless will not achieve that rise in temperature if incoming water is cold.
BTUs put out by tankless burner has limit.
If incoming water is colder than certain temperature, then tankless cannot raise temperature quick enough as water passes through burner.

5) You might also need a tempering tank, to modify cold water in winter:
http://waterheatertimer.org/Tempering-tank.html

6) Suggest you also read the yearly maintenance required for tankless.
For example tankless are prone to lime build up and need to be de-limed each year with vinegar.
Lime build up will certainly affect water temperature.

7) Following 2 links might be helpful for tankless owner:
http://waterheatertimer.org/pdf/Delime-tankless-water-heater.pdf
http://waterheatertimer.org/pdf/Paloma-Tankless-Error-Codes.pdf
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

1) Read your manual

2) De-lime unit on yearly basis:
Search google and Utube for 'de-lime tankless'
They make special fittings that permanently attach to water ports so you can delime each year.
Research shows that reqular de-liming will not restore tankless efficiency.
http://waterheatertimer.org/pdf/Delime-tankless-water-heater.pdf

3) Typical manual shows temp information on page 22-23. Search pdf for 'temp'
http://waterheatertimer.org/pdf/Rheem-RTG74IndoorOutdoor_owners.pdf

4) Read maintenance steps shown in manual
The word maintenance appears throughout the manual

5) Search fixya questions on tankless to glean information about your unit:
Older answers have more responses, and each seems varied as techniques succeed for one person but not another.
The quantity of unanswered questions and vague answers reveals why Rheem suggests qualified technician be added to your rolodex-wallet
http://www.fixya.com/tags/rtg_74pvn

6) Other useful links for tankless owners:
http://waterheatertimer.org/pdf/Paloma-Tankless-Error-Codes.pdf
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Open following link for rheem tankless resources, including manuals, error codes and typical maintenance.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

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