Stiebel Eltron tankless heater Tempra Plus 36 issue

[TravisOKC]

I have a tankless electric Stiebel Eltron Tempra Plus 36. It is probably 7 years old and have worked perfectly until yesterday afternoon. The unit had no power. The temp display was not lit up. I checked the circuit breaker and it had not been tripped. I did notice the pressure reset switch on one of the tanks, right side one, needed to be reset. When I pressed it the system powers up and produces hot water. The shower was able to be used for a normal shower, 10 minutes or so. The issue is that once the water is not in use the system shuts down after a few minutes of non use. I can keep resetting the thermal cut out but it just trips the reset again. I have taken out the flow sensor and it seem to be fine, I also looked at the screen on the inlet and there is no build up. I called a plumber and told him my issue he said he didnt work on these units and would just sell me a new system.

Is it possible or probable that all I need is a new safety thermal cut out for the one that keeps resetting?

any help is appreciated!

Thanks, Travis

 

[GReynolds929]

You could have an element failing and overheating the water.

 

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[Fitter30]

Have u ever cleaned it with vinegar and a pump? Yearly? Looked a couple of install manuals none of installation manuals don't write anything about mineral built up except in faucets. Heater is full minerals encapsulating the elements. Look at youtube cleaning a combi boiler.