No hot water at all when I turn on the hot water faucets nothing nomad I would hear the burner kick on but nothing what so ever

Light pilot, turn on hot water faucet in tub and run until there is no air in the water, turn burner on.

Check the heating elements for continuity.

Fix problem immediately same day, yourself, for $385, by replacing whole thing:
http://waterheatertimer.org/How-to-install-gas-water-heater.html
Bosch posts some service manuals: or contact Bosch. Lack of error code indicates failed PC board? or bad single-handle faucet cartridge?
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
Check for crossover where bad faucet cartridge allows cold water to enter hot pipe, so hot water is not drawn through tankless and burner does not activate... but this might not be problem since you hear the tankless clicking
http://waterheatertimer.org/Crossover.html
Call local service technician to catch up on required yearly maintenance.

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

Test for crossover, where bad faucet cartridge or recirculation check valve keeps hot from reaching taps
http://waterheatertimer.org/Crossover.html

Add a comment and say what you find

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

Feb 2013
1) Copy following links for Intellivent gas control service manual, low hot water pressure, and crossover:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/Low-hot-water-pressure.html
http://waterheatertimer.org/Crossover.html

2) Unknown if tank has hot water > that is first thing to check.

3) Unknown if air intake screen located under burner is clogged with dust that cause combustion chamber to overheat, tripping FV lockout and breaker TRD glass vial.
Requires removal of combustion parts, replacement of TRD, blow out air intake screen, reset intellivent

4) Unknown if there is error code.

5) Rheem does not post service manuals.
However this unit can probably be repaired.

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

You have gas water heater with working burner.
But not getting hot water at faucet?

1) Bad faucet cartridge. Test for crossover. Copy following link:
http://waterheatertimer.org/Crossover.html


2) Is there hot water inside the tank? Open drain valve and check for hot water.

3) Drips and leaks: Turn off all taps and put ear against pipe and listen for water leak.
Water leak can run all the hot out of tank.

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

http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html#flow
1) Tankless require minimum flow rate before burner will activate.
2) Sounds like the water pressure drops quickly when faucet turns on. This implies combination of problems including sediment build up inside lines, crossover at single-handled faucet, or sediment filter clogged or water softener clogged.
3) Low flow faucets can reduce needed flow rate.
4) Other problems can contribute: sensor failure, loose wires, PC board failure, high temperature setting, cold incoming water temperature during winter months.

Turn of the hot water valve and turn on a hot water tap in the house. If You have water flow, then you have a problem with a faucet (usually a shower valve). Go to the shower valve and see if you hear water running. If so that is likely the problem. Otherwise there is not enough gas to fire the unit that far and it will fail out. Check the manual most people install these units wrong. If you install it to code then you did it right. If you install it to the manufacturer's specs, you installed it to code and it is right. Then the only adjustment is with a Calibrated CO2 analyzer (instructions in the manual).

Check power to well pump, isolation valve is open, faulty pressure switch. If only one faucet you have a plugged screen on the end of the faucet

THE WATER IS RECIRCULATING IN THE UNIT. MAYBE CAUSED BY THE ACID. TRY INSTALLING A BACK FLOW PREVENTER