Hi All, I have retired on a boat & fitted a Duetto Hot water system & initially switched it on in 12 volt & left it on as I have 720AH of LiFePo batteries & 1560 Watts of solar, so power is not a problem. What I would like to know. Has anyone else used their Duetto on 12 Volt only & have they had any problems. I have burned out 2 - 12 volt elements. The second in only 4 weeks. The 240 side works fine on the inverter when left on permanently it runs for 2 minutes every hour & a half to keep the water piping hot. I'm figuring I should only turn it on a half hour before I need it??? There are no water problems no leaks & it is set up below both inlet & outlet so it can't run dry. Has a dedicated DC contact breaker in the, tinned, 8mm square power wire with a trip current of 33.75Amps. The thermostat checks out Ok. Voltage is always between 12 & 13 volts. The hottest the Positive wire has been is 35.8C so below body temperature. This has me really stumped??? It has been suggested it is electrolosis or Galvanic action but no stray currents have been detected anywhere in the unit & there is no evidence of corrosion on the elements.