Why code 760 .then waterheater turn off

Bad thermocouple

This indicates a reduced supply of water to the heater. Check water flow through the tap has not been reduced If so, check filter area

1) Unknown water heater type, brand and model.
Check for crossover first to eliminate plumbing problem.
http://waterheatertimer.org/Crossover.html

2) Add comment with more information about water heater for possible assistance, and give type, approximate age etc.

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

Clogged cold water nipple or clogged hot water nipple.
Is water hot at drain valve?
http://waterheatertimer.org/Low-hot-water-pressure.html

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

Richland tankless is made by Rheem.
C7-76 is communication fault with remote.
Turn off power at remote and wait 5 minutes, turn power back on at remote, and see if problem clears.
If problem continues, read below:

Before calling service technician, open following links for troubleshoot resources including error codes, Rheem chat, typical maintenance manual:
http://waterheatertimer.org/pdf/Rheem-error-code-C7-76.pdf
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Tankless water heater, more than any other type of heater, need to be maintained.
Maintaining tankless will probably not affect C7 76 fault code, but can prevent many other common error codes.
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

if water heater heats up and after water is hot turns off you need to replace the control unit (part where all the little pipe hook into) should have an 800 number to call where you can give serial number and model number to see if still under warranty because part is as expensive as new water heater

Hi and welcome to Fixya.

Here are 2 manuals that should help you in troubleshooting your RV hot water problem.

Multiple times there is a ref. to resetting the reset switch for 30 seconds on the unit (cover removal required)

For the ignition:

http://www.atwoodmobile.com/manuals/waterheaters/MPD%2093757%20PS%2011.19.07.pdf

For the water heater:

http://www.atwoodmobile.com/manuals/waterheaters/MPD%2093050%20PS%204.9.09.pdf

The manuals as written are full of warnings mixed in with meaningful text. (Not user friendly)

Should I assume you have turned up dial on waterheater yet??
Please rate.

There should be a cut off vave installed on cold water inlet a top of waterheater if not there you will need to cut off at meter,curbside.

Please rate. Thank you. jj505

Clear the area around the bottom of waterheater so as to allow air flow around mesh area built into base of water heater and or open unvented door passages involving waterheater. This mostly a safty issue which seldom occurs if not remedy quickly.

Please rate. Thanks JJ505