I have a 606, replaced both elements, and thermostats. There's 123v on both elements, but water does not get hot. Prior to that, breaker kept tripping, I assumed due to bad elements.

SOURCE: no hot water

If the water does not heat, then you have to troubleshoot to find the problem. With a voltmeter determine if 240VAC is actually getting to the water heater. Take care here - a defective circuit breaker can give a false 240 volt reading - check for the 240 volts across the upper element (i.e. when the 240 volts has a live load on it, not just an open circuit test).
Also, remember, the upper element has priority over the lower element, and if the water is cold, the upper element will try to turn on and this locks out the lower element (only one element is allowed to heat at any given time). The lower element comes on ONLY after the upper thermostat is satisfied. Therefore if the upper heating element is burned out you will never get any hot water. If you suspect this, TURN OFF THE POWER TO THE HEATER and take a resistance check of the upper element.

Allen Neal

• 359 Answers
• Posted on Feb 07, 2009

SOURCE: Main breaker tripping

replacing the main is a possibility and i saw someone suggestion to ck load on each leg of power , also a good idea but one thing i have also seen do this is a loose or corroded connection in the meter base or disconnect which causes a process called electrolysis that is a flaking away of the conductor itself in the meter base or disconnect feeding the panel main breaker and causing heat build up internal to breaker and making it trip but if you replace the main that is the time to check all these connection and it would not hurt to apply a little no lock or some other brand of oxidation inhibitor

SOURCE: Bunn coffee maker trips the breaker

It is possible that you have a short in your limit thermostat, but most likely this is caused by small holes in your main heating element. these units start to split length ways down the element, causing a short to ground through the water. These elements are readily available at your local Bunn repair shop.

SOURCE: Rheem Hot Water Cylider Thermostat keeps tripping

Sounds like you have a faulty thermostat.  This is the unit that detects the water temperature, and if it is not where it is set, will kick the switch to allow electricity to flow to the elements you replaced. The thermostats are relatively cheap and if you have the knowledge to change the elements, changing these thermostats should not be a problem.

SOURCE: gfci breaker keeps tripping

It may not relate to this problem but my exterior GFCI breaker kept tripping after a winter warm spell. Solved it by drying the breaker with a hair dryer for about 10 minutes. Warm wet air had condensed inside the breaker.