Rheem tankless shuts down on it's own.

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

Gene

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

Rheem Paloma tankless computer? No error code? One possible cause; Crossover caused by bad single handle faucet cartridge drawing cold water into line causing shut down of tankless burner?
Copy following links for resources:
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
Add a comment as needed.
Gene
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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

You received recommended answer posted ago.
Probably same answer today:
Don't install tankless, especially in location where there is no service technician available unless you expect to heat water by setting tankless out in sun.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Repair any brand tankless, any error code or problem, same day, yourself for $385:
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Add comment and give link to service manual that you located.

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

Water in hose coming from gas valve caused unit to shut down how do I get water out

Rheem makes a number of tankless models
http://www.rheem.com/products/tankless_water_heaters/

They make a tankless 95 outdoor series
http://www.rheem.com/product.aspx?id=EBA80FAA-3C0F-411D-AF83-82061C28ED1B

The 95 outdoor series spec sheet says .4 GPM minimum activation and .26 GPM flow to keep burner activated. The colder the incoming water, fewer users can take a shower at once.
http://globalimageserver.com/fetchDocument.aspx?id=ea5f0816-dfd4-4bcf-a605-79945619f5bb
The .4 GPM and .26GPM numbers are fairly typical for tankless units.
These numbers are good when the unit is new.
After a few years the number may be different because the tankless is a high-tech machine with sensors that are susceptible to particulate in the water, and susceptible to perfect-functioning of other parts in the machine.
The outdoor series spec sheet says the tankless is good to minus 30 F.
But remember that's when the unit is new.
Outdoor tankless water heaters have an electric heater that keeps water pipes inside the unit from freezing, as long as electricity is ON.
If electricity goes off, the house stays warm inside for several hours.
But a steel box located outside would get cold immediately without electric heat.
The electric heater adds standby cost to operational expense.
The tankless has a heater, but you still have to protect the incoming and outgoing pipes.
If your incoming water is very cold, the tankless heater may not be able raise the temperature fast enough to give two showers -or- even 1 shower depending on age and efficiency and capacity.
You can add a tempering tank located in naturally warm area that passively pre-heats incoming water before it enters the tankless burner.
It might be best to locate tankless inside the house >> and use direct vent through the wall for both incoming air supply and outgoing vent gas.
If incoming air is taken directly from the living space, then tankless will draw air into the house through cracks and around doors.
A lack of sufficient air, or poor air quality can cause the burner to shut down.

When buying a tankless, read the spec sheets and really ask questions about everything you don't understand.

This is something you will have to contact rheem about due to the fact you don't have a fault code

I am not sure if this is it but I had mine at too high of a temperature therefore I was not using enough volume of hot water to keep the heater on. They have a minimum amount of flowrate to sustain. Try turning the water temp down to 125-130. Hope this helps

Contact Rheem; the Burner control unit has lost comm with the remote...the part is warranteed for up to five years.

your not getting enough fresh air to it. where is it located? you need 1 square inch per 1000 btu's. it's having irregular combusion.

have you checked the error codes on the heater?
you can do this by powering off the controler and pressing the up and down keys for a few seconds. this should take you into the diagnostics mode scroll using the up and down keys till you find the one that has the letter E on it and that will give you the last 8 error codes write them down and get back to me