Fast corrosion waterheater Isotemp 40HXCV

Thanks for that.

My H301 spent most life on an isolated mid stream mooring. Very rarely plugged into a mains. The 315 is often in marina. Both have galvanic isolators, but that doesnt help if there is earth leak current.

The 301 calorifier was clearly a deficiency in Braze/build quality. The 315 is an Isotemp buget model as I said using mild steel pressure vessel with vitreous enamel lining, the rust [and there was a lot of rust] was in beween the rubber gasket, the pressure vessel, and the header that holds the immersion heater and the thermocouple pocket for the dual over heat sensors. The magnesium anode was pretty big and only part used. I doubt if galvanic action was the cause, I have seen similar failures on French Domestic boilers, that use this mild steel pressure vessel protected by vitreous enamel coat.

This evening was speaking to a yacht chandler friend, who said his experiece of Isotemp boilers and many other calorifier manufacturers  was a 10-15 year life.