Can i get a manual on a bosch gruppe water heater

the low pressure/flow minimum is for safety and protection of unit and no adjustment to do so

Is it gas or electric? if it is gas and has a pilot, and the pilot is out. If you don't smell gas go through the start pilot proceedure. when the pilot is running it produces a small electric current sufficient to hold the main gas valve open; then the temperture sensor allows the unit to keep the water heated.

Is this a water heater? Bosch site might have manual. And service bulletins, but I have not heard of that model.
http://www.bosch-climate.us/Bosch-Hot-Water/
Call local service technician who is qualified to work on tankless computer that heats water.
You can fix any brand tankless computer, any problem, same day, yourself by replacing 1 part: the whole thing:
http://waterheatertimer.org/How-to-install-gas-water-heater.html
Gene
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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) Web search 'WR11 water heater .pdf' shows Bosch WR11 manual
http://www.boschsupportline.nl/content/files/TechDocs/Geisers/6720607884.pdf

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

http://documents.junkers.com/download/pdf/file/7181465057.pdf Sometimes there are several parts on this model to find buit beware on some marketing technical made differences inbetween one year of build there can be some modifications inside.

Succes

The manuals don't mention a battery.
Open following link for Bosch contact information and troubleshoot resources.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Bosch gas 10p.
Word search of manual does not show battery.
Save the manual for future problems.
http://waterheatertimer.org/pdf/Bosch_10P-installation.pdf
http://waterheatertimer.org/pdf/Bosch_10P-water-wizard.pdf

Bosch electric under-counter P10-P15 resources:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/AristonModels/P10P15Models/Troubleshoot/tabid/653/Default.aspx

Bosch P10 manual does not show battery during word search
http://waterheatertimer.org/pdf/Bosch-P10_P15_English.pdf

1) Dirty water implies degraded metal inside unit:
The anode rod protects metal parts. Once anode is depleted, metal parts react with water.

2) Open following troubleshoot pdf showing Ariston parts
http://waterheatertimer.org/pdf/How-to-Troubleshoot-Bosch-Ariston-Water-Heater.pdf

3) Ariston manual: Read manual cover to cover, make sure water heater receives yearly maintenance as outline in manual.
http://waterheatertimer.org/pdf/Bosch-GL_English.pdf

4) Information on anode rods
http://waterheatertimer.org/Replace-anode-rod.html

5) For Bosch gas and electric tankless: Open following link for troubleshooting resources, including Bosch contact information, typical manuals, error codes, tech support, parts, fuel-saver calculator, service bulletins, water heater forum, fixya links, disclaimers, and links for finding service technician.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

6) Add a comment with your experience so others with same-similar problem can benefit.

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.

i have a junker water heater. what side does the cold water pipe go the the geyser

first find out from your manual what the flashing red light means...that should narrow your search---could be a thermocouple shot,a rubber diphragm in the gas valve has weakened and not operated, or gas pressure into the appliance may suddenly be too low, or springs in gas valve may have worn out---very many possibilities

go to this site, have your model number at hand.
http://www.boschhotwater.com/HelpfulResources/BrochuresManuals/