Champion uh100b over heats, trips the limit on the tank, replaced limit and that was not the problem

If you have already descaled your Tempra 24 Tankless water heater and replaced the flow sensor, but the high limit switch is still tripping, there could be a few other possible causes of the issue: Malfunctioning thermostat: A malfunctioning thermostat may cause the heating modules to overheat, which can trip the high limit switch. You may need to replace the thermostat if this is the case. Insufficient water flow: The Tempra 24 Tankless water heater requires a minimum flow rate of 0.5 gallons per minute to operate properly. If the flow rate is too low, the heating modules may overheat and trip the high limit switch. Check the water flow rate to ensure it meets the minimum requirement. Electrical issues: If the wiring or electrical connections are faulty, it may cause the heating modules to overheat and trip the high limit switch. You may need to inspect the wiring and connections to ensure they are intact and properly connected. If none of the above solutions work, it may be best to contact a professional technician for further diagnosis and repair. It is unlikely that you would need to replace the entire unit if the issue is isolated to a single heating module.

Why Does My Electric Water Heater Reset Button Keep Tripping? So the red reset button on your electric water heater keeps popping out and needing to be reset.
Here's the most likely problem: The water in your water heater is getting too hot.
When the water temperature in your water heater exceeds 180°, the red reset button (also known as the high-limit switch) trips. This tripping protects you from getting scalded or burned when using hot water in your home.
OK, but then what's causing the water in your water heater to get so hot? The most likely cause is a bad thermostat.
How a bad thermostat causes your water heater reset button to trip Electric water heaters have a lower and upper thermostat-one for each heating element.
The thermostats are responsible for controlling the heating elements. When the water has cooled off, the thermostats kick on the heating elements to heat the water. And once the water has reached your desired temperature, the thermostats shut off the heating element.
(This is very similar to the way your heating and air conditioning thermostat controls your home HVAC system.)
But these thermostats can go bad. When they do, they sometimes get stuck in the "on" position. This means that that the heating element continues to heat your water, eventually causing the high-limit switch to trip.
The fix: The bad thermostat needs to be replaced. A plumber can use a multimeter to test the thermostats and find out which one is bad.
Other problems that can cause your high-limit switch to trip While a bad thermostat is the most common reason your water heater's reset button may trip, it's not the only one. Other common causes include:

• A shorted heating element-It may be that the thermostat is working just fine and shutting off the heating element. But a short in the element is causing it to continue to heat your water.
• Loose wiring-A loose wire in the water heater can generate heat that can cause the high-limit switch to trip.
• Bad high-limit switch-The switch itself may be malfunctioning and tripping when it shouldn't be.

Get a professional plumber's help

Do you live in the Minneapolis-St. Paul area and need a reliable plumber to help you troubleshoot your water heater problem? Contact MSP Plumbing. We can usually fix the problem the same day.

Your machine has an "upper broil hi-limit thermostat" that has likely tripped and is not allowing L2 to your element... Range Stove Oven High Limit Thermostat WP71001844 If you get no heat anywhere, reset your circuit breaker! It can trip halfway and you can't tell by looking at it...

Hi limit device trips prematurely (should only trip when oil temp reaches 450F). Check if the hi limit sensing bulb (located inside the fryer tank, between fire tubes) is not touching the fire tube because if it does, it will sense the heat from burner flame which is much higher than oil temp.

Most electric hot water heaters have two thermostats, one near the top of the tank and one near the bottom, and are covered by removable metal cover plates. The thermostats are pressed firmly against the bare metal wall of the hot water heaters tank.

The top thermostat usually has a high limit switch that will trip if the water gets too hot. When it trips it shuts off the electricity to both the upper and lower heating elements.

To reset the high limit switch there is usually a red button that you must press. When the upper limit switch trips it is often an indication that something else has gone wrong with the heater.

When the top of the tank is hot the upper thermostat removes power from the upper heating element and transfers the power to the lower thermostat and heating element. If the lower thermostat is defective, then the lower portion of the tank will not be heated and the supply will be greatly reduced.
Check for power at the upper thermostat terminals where the power is sent to the lower thermostat and heating element. If there is no power then the upper thermostat should be replaced. If there is power then check for power at the lower heating element. If there is no power at the lower heating element then replace the lower thermostat.
If there is power to the lower heating element then it should be getting hot. If it is not, replace it. Another possibility is a broken dip tube. Check for a broken dip tube and replace if necessary.

Hope this helps out

The controls of electric water heaters are designed so that at no time are both the top and bottom heating elements energized. Nearly all electric water heaters of this capacity in the US & Canada (other places, too) operate on 240 Volts.

When the water in the tank is below the set point of the thermostat (in your case - 120 degrees), the top heating element is expected to be on - (unless there is an issue with the top thermostat or limit switch). The top most control is the "high temperature limit". It is identified by the reset button on it. Make sure this isn't tripped by depressing the button. If it clicks - it was tripped and should start to make hot water at this point. If not tripped, you should check for the presence of 240 Volts between the heating element terminal screws. Do not measure from ground to a terminal screw and believe 120 Volts is "good". To make heat, you need 240 Volts - not 120 Volts measured across the terminals - not to ground. The amount of heat created running at 120 Volts is only 1/4 of what it will do at the correct voltage.

If you don't measure 240 Volts on the top element, check the bottom element in the same manner described for the top element.

If unable to measure 240 volts on any element, either there is a problem with the power source (blown fuse or circuit breaker), high temp limit switch, or thermostat(s).

If 240 Volts is present on either heating element, and water is not warm / hot in 30 minutes or so, a defective heating element is suspect. You can change controls without draining a tank, but replacing elements will require draining the tank first. Do not power the water heater without first filling it.

You can read a very detailed "how to" article about checking water heaters here.

I hope this helps - and good luck!

First things first, you are not supposed to have power to both elements at the same time. The top element comes on and heats the top of the tank, then the top goes off and the bottom comes on. Now, check power on the top element, put your meter probes on both screws on the element, you must have 220 to 240 volts between these two screws. If the voltage is good then you have a bad element, if the voltage is not there, then you need to check the voltage at the top 2 screws on the upper thermostat, if it is okay there, maybe the hi limit has tripped, push the reset button on the top thermostat, if it is tripped it will click and start heating right away. If the hi limit is not tripped then you will need to replace the upper thermostat.

the 'easy' answer would be a tripped high-limit switch. Inside the generator box, there is a resettable circuit breaker to the heating element, on the top of the water tank.
kill the power to the unit, take off the shell and look for the pushbutton.
If that is the problem, there is a likely chance that the temp sensor in the shower is not working so it overheats and trips the high temp limit.

possible problems not knowing age of unit the
control valve could be sticking open allowing gas to continue to flow until high limit is reached and shuts down valve another possible problem with the newer style back flow preventer being install by water companys the rapid heating and expansion of the water over pressures the water system causing releif valve to pop open and reclose most water heater manufacters are recommending instalation of an expansion tank to allow the growth in volume of water somewhere to go is valve constantly leaking or only during heating cycle if you could supply additional information does unit only leak when heating
or is steam expelled when releif valve opens
t-stat not opening gas valve sticking partially open
bad high limit bad pressure releif valve no expansion tank to allow for thermal expansion if steam is present and unit is boiling water inside replacement of water heater for safety concerns,would be reccomended if only water and pops couple of times water temp not over 140 degrees after most hot water has been used out of tank and is reheating most of capacity probably lack of expansion tank as the releif valve is the final safety device on a water heater is of great concern
the temp control gas valve or high limit are supposed to shut unit done long before the safety limit of releif valve is reached

The wash tank heating element is control by 1. the dual Float switch 2. The temperature control 3. the high limit thermostat 4. Contactor 5. tank heat fuse 6 element itself. Hope this help. God Bless.