My heater cz488 will not come on after pressing reset button on the bottom

Problem with overheat cutoff. Press reset button on the control panel.
Before calling service technician, open following link for Bosch troubleshoot resources.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
Recommend that people not install tankless water heaters, or heaters they cannot repair themselves since all costs are energy.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

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

You have electric water heater.
You have top and bottom panel, so water heater is 240Volt.
No hot water because ECO reset button tripped.
Water heater works correctly when reset button is reset, so electric power and circuit breaker are good. Water heater wiring is probably good.

Problem is most likely bad thermostat.
I usually replace both upper and lower thermostats.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

If problems continue after replacing thermostats, then test and replace elements.
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html

to clear the 991 Takagi code, simultaneously press the bottom 2 grey buttons of the four just to the left of the flashing LED light. When the LED stops flashing, release and then press the reset button on the black panel about 8 inches above that

Yes dothis with the power on ,If it kicks rightbback open then try to find cause befofe trying agaim. Thanks

You can open the top up again. I would not turn the temp higher than 130 degrees, maximum. However, there should be above the thermostat a red button. This is where the power wires connect to the thermostats and heating elements. Sometimes this button needs to be reset, press it and discern if you hear a click sound. This means that the high temperature safety switch has tripped open and you had to manually "reset" it. There are two thermostats by the way. The water heater usually works this way. There are two thermostats and two heaters. The upper tank heater turns on first and it heats the top half of the tank. Then when the thermostat above is satisfied it then allows the bottom heater to come on and heat the bottom half of the tank. You might want to set the bottom heater thermostat as well. This is made this way because it is actually faster and more efficient to heat the top half first and the bottom half secondly. Try this first with the reset button. We could check voltages, but that requires a level of knowledge and safety that I am not sure that you are comfortable with. Pictures of the upper and lower thermostats and connections will help if the "reset" does not do the trick. By the way, not meaning or implying anything, but did you move the thermostat in the right direction? Sometimes the dials can be confusing.

Certain water gas water heater models feature electronic controls with a flammable vapor sensor installed on the bottom portion of the water heater unit. This sensor is designed to shut off your water heater system to prevent fires in case flammable vapors are present within the area. If your flammable vapor sensor caused your water heater to shut down, check the area immediately for leaking gas or other flammable products. Common household chemicals such as bleach can also trip the safety system as well as unsuccessful burner ignition attempts. I'm not sure what control your unit has, but on a White Rodgers here's how it goes.


White Rodgers Intelli-Vent PowerVent Control Equipped Models

1. Step 1 Turn the water heater's blower switch off and disconnect the power cord for the water heater (refer to your particular model's operation guide for the exact location of the blower switch). Disconnect the Molex connector attached to the bottom of the control pad (the left most connector with five pins).
   
2. Step 2 Turn on your multi-meter and set it to read resistance or "ohms". Connect one of the multi-meter's probes to the number two pin and the other probe to the number three pin of the Molex connector (middle black wires). If the reading on your multi-meter reads below 9k or above 45k ohms, the flammable vapor sensor is faulty and in need of replacement; you cannot reset the system until this issue is resolved.
   
3. Step 3 Reconnect the Molex connector to the bottom of the control pad, reconnect the water heater's power if and turn the blower switch to the "ON" position. Press both the left and right buttons on the control pad at the same time. Wait for the green light on the control pad to blink and press the following buttons in sequence: Left, Right, Left, Left, Right, Left, Right, Right (you will need to perform these actions within 30 seconds of reconnecting the power cord to the water heater in order to be successful

Red button on upper thermostat just press it to reset.

1-First check for power to water heater and remove acces panels on heater to check power at thermostats. Thermostats have a reset button on them that trip and can be pressed to reset.

2- If none of the above have changed any thing and you have power you may have elements gone bad.

If an element is gone at top you will get scalding hot water then go to cold.

If an element on the bottom is gone you will get luke warm water then will get cold.

Willard when you say it throws the reset button,do you mean the breaker on your fuse box of your home?
If you mean that then yes it could be a bad element.The bottom element takes all the abuse on a electric hot water heater. They can short out,and need to be replaced.

i guess it is electric ,check bottom element reset button .remove bottom cover with power off look for a button on bottom thermostat or limit if find push it to reset ,,then set the thermostats , set top to desired temp and the bottom at least 10 degrees more ex. top 130 bottom 140 this might prevent problem reoccurring if this not problem bottom element could be burned out.replace ele