20 Most Recent Jacuzzi 21" Vent Kit J-SVKIT2 Questions & Answers

My Navien is doing the same thing, and it's 6 days old. The older unit did the same thing as well... I'm guessing it has nothing to do with the unit, and something to do with the line... I'd love to get to the bottom of it as well.. :(

Follow the link, you need to "Descale" the heater. Tankless Water Heater DeScaling How To Flush

If your GFCI is tripping, it could be due to a bad heater element, pump, blower or ozonator. To determine which component is causing the problem, unplug the components one at a time and turn the breaker on. If the breaker does not trip after unplugging the pump, ozonator or blow, you've found the problem and you can now replace that component. If you've unplugged all three components and the breaker still trips, it's likely the heater element. Hiring a technician or replacing the heater is the next best course of action.

Theres no fix for your problem cause your water heater is fu.k.d up.  Go out and buy you a new one and don't forget the expansion tank.

There is a ground fault somewhere...you need to isolate it with an ohm meter.

you possibly have a bad heating element