Don't have hot water

Oh some of these there was a small black heatexchanger just for hot water they some times block up . or it could be a blockage in the water section where it flows in .I know Valliant have a very good tech line and fitters who do house calls .

It could be element shorted to ground through steel tank, so don't touch tank when breaker is ON.
Or you have undersized 12 gauge wire and 20 amp breaker and the heat has loosened breaker on the busbar. Breaker trips when heat exceeds breaker limit. Jiggle breaker and listen for crackling sound.

To restore hot water now:
Turn off circuit breaker, and open top cover then Push in reset button on top of heater to restore functionality. Put back insulation and factory cover.
To fix water heater: test and replace bad element.
http://waterheatertimer.org/How-to-test-water-heater-element.html
If problems continue
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#trip-breaker
http://waterheatertimer.org/Troubleshoot-household-electricity.html

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

Which type Richmond water heater?
Is this a tankless water heater or tank-type?

Tankless are notorious for 'cold water sandwich' under exact conditions you describe. You might need tankless with larger BTU burner.
Don't install a tankless.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

If you have tank-type water heater, then I suspect a clog in the hot water line, or single-handle faucet cartridge in show is going bad.
Same problems can contribute to tankless problems.
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

Check that you are receiving 240Volt across top 2 screws on upper thermostat.
Copy following link for troubleshoot resources:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

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

1) Call Rheem. I don't know the number outside the US.
1-800-432-8373
2) Contact local plumbing supply and ask who sells the Rheem unit. Then call that dealer and inquire about rating.

You have 2 problems with several possible causes:
You have 10-year-old electric water heater that was reinstalled after falling down, and doesn't heat the water.
And you have no hot or cold water pressure, and no pipes are leaking.

1) First problem is lack of water pressure throughout house.
Turn on outdoor spigot nearest to water meter.
This spigot will tell you if problem is inside the house or between the house and meter.
If spigot runs full force, then you probably have clogged pipe where water heater connects to main cold line, or the main shut off valve got clogged with sediment that broke off inside the pipe when you were working on water heater.
Open and close shut off valve to see if that helps. Then disassemble pipes and track back the problem. Put pressure gauge on water heater drain valve to watch pressure drop when turning on indoor faucet.
Read following information:
http://waterheatertimer.org/Low-hot-water-pressure.html

Water heater doesn't work:
Test across wires at top of heater to see if you are getting correct voltage:
If tank is receiving correct voltage, then no hot water puts suspicion on upper element or upper thermostat, or both.
Open following link for electric water heater troubleshoot steps:
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html

As long as the water heater is not leaking or not big enough that would be the only reason to replace heater. If you are running out of hot water or it's cold, check the power source first to make sure you have power to heater. Then check the reset button on the top thermostat and make sure it's not tripped if it is it wil not heat. If so press red button aloow it a little time check for hot water.
Next step woul dbe to turn power off and drain water to replace both elements out. Once changed out turn water back on and open a faucet to remove air out of the wtare lines. Once you get water flowing out of water lines now you are ready to turn power back on. allow about 30 to 40 monutes and you should have hot water.

Consult your owners manual.
http://www.bosch.com.au/content/language1/downloads/70R_UserManual1023.pdf
Heres a new one if you don't have or lost yours. You can't, you got bad advice. tankless system don't have a running pilot light. They operate by detecting water flow and then turning on. Many also state on the lighting instructions to NEVER try and manually light the pilot. Try Bosch tech support. Lowes sells Bosch heaters and they might be able to help you get the support number faster. Hope this helps but please don't go sticking a flame inside there.

I don't have specific suggestion for tankless tripping breaker or if that is a circuit breaker problem or a tankless problem.

1) Move wires to another same-size breaker and see if problem persists.

2) Compare amp draw on tankless label with wire size and breaker size amp rating.
For example 30 amp breaker using 10ga wire is rated for 80% of listed amps or 24 amps.

3) If you are drawing full 30 amps, then 30 amp breaker is getting hot. Breaker trips with heat. Older breakers can trip more easily.
http://waterheatertimer.org/How-to-replace-circuit-breaker.html

4) Before calling service technician, open following link for Bosch troubleshooting steps.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

5) Be sure to read manual for yearly maintenance requirements.

6) Add a tempering tank for incoming cold water problem.
http://waterheatertimer.org/Tempering-tank.html

7) All gas tankless brands can be repaired by homeowner for $330.
http://waterheatertimer.org/How-to-install-gas-water-heater.html