I have a customer who would like a Bosch AE-9.5 tankless water heater installed in the master bathroom. The master bath is located at the far end of the house & they are wasting a great deal of water waiting for hot water to the bathroom. Can the AE-9.5 be installed at the end of the existing hot water line from the whole house water heater so that it will bring the water collected in the pipe up to temp immediately.

http://waterheatertimer.org/pdf/Bosch-AE115-AE125_manual.pdf
Bottom page 10 troubleshoot

Add tempering tank to pre-heat cold incoming water
http://waterheatertimer.org/Tempering-tank.html

Call service technician

Delime heat exchanger.
http://waterheatertimer.org/How-to-delime-tankless-water-heater.html

Replace with tank type?
http://waterheatertimer.org/How-to-install-electric-water-heater.html
Gene

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

Depends how far away the tankless is located.
Tankless are not instant hot water heaters
Also check for cross connection
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://waterheatertimer.org/How-to-install-under-counter-water-heater.html

Gene

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

This is a "point of service" tankless water heater that was manufactured by BOSCH. BOSCH is now Bosch-Climate.us. Technical support is available at 866-330-2729. P.S. check this site: http://tanklesswaterheaterz.com/bosch-ae-9-5-powerstar-1-5-gpm-point-of-use-indoor-tankless-electric-water-heater-reviews/

1) Cheapest and most reliable solution: Install tank-type electric water heater from local box store for $250. Get store coupons, offer 10% off store price. Repairs are made same day with generic off-the-shelf parts.
http://waterheatertimer.org/pdf/How-to-install-electric-water-heater.pdf

2) Install grundfo water pressure boosting pump.
http://www.ronhazelton.com/projects/how_to_increase_water_pressure_in_your_home
http://waterheatertimer.org/How-to-solder-pipes.html

3) Remove areators and low flow shower heads, Maintain unit as shown in product manual: Delime tankless unit yearly, Clean water filter monthly.

4) Call city and report low pressure and report issue as fire hazard, move to different apartment. Call apartment complex and ask why they didn't read flow requirements for tankless before installing tankless.

5) Call Bosch 866-330-2729 and complain that nobody read the flow requirement or tested local water flow before installing tankless.

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

All resets and breakers trip with high heat.
Do you mean the tankless unit is tripping the 40 amp circuit breaker?
Or the thermal cut-out, located on unit, is tripping?

Is this a new installation?
Or was the tankless working before and stop working?

Copy following link to check wiring.
AE 9.5 requires 40 amp breaker and 6 gauge wire.
http://waterheatertimer.org/How-to-wire-Tankless-electric-water-heater.html

If the unit is tripping the thermal cut, -out, then product manual says to call Bosch or service technician.
Call Bosch 866-330-2729
http://waterheatertimer.org/pdf/Bosch-Powerstar-AE3.4-7.2-9.5.pdf
Thermal cut-out can trip if water flow is too low.
Try changing power selector screw from Hi to Lo so only 1 element is ON. See diagram page 6 of manual.
Adjust the 'outlet service valve:' The manual recommends that a ball valve be installed between hot outlet and faucet. Adjust the valve so more water flows to faucet.
Remove aerator, clean aerator, don't use low flow restrictions or low flow shower heads, replace leaky faucet cartridge on single-handle faucet.

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

Before calling service technician, open following links for Bosch error codes, and contact information, and possible product manual for your model, etc:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
http://waterheatertimer.org/pdf/Bosch_EA_error_code_troubleshooting.pdf
http://waterheatertimer.org/pdf/Bosch-GWH2400ES-error-codes.pdf
http://waterheatertimer.org/pdf/Bosch_A4-E4_error_code_troubleshooting.pdf

Error code AE is not shown, but error EA means "burner flame not recognized by control unit when water is flowing"

There is also error A3 and A3 E3: jumper connection is not correct

You need to have the flow switch looked at. The low flow of the water to the lavs and the kitchen sink, they all have as small demand next to t bath or shower,
Tom

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

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.

It sounds like you have a plumbing cross over or a poor install. Check boschhotwater.com to find a service technician and have a Bosch service provider look at it.

That is a single phase hot water heater. Hope this helps