Originally Posted by
jack14r
I think that the Marathon water heaters are made by Atwood,they do have a rectangular case,the two are wired so that only one element is on at a time,they have a heat exchanger to work from the DD or Webasto,the valve must be adjusted carefully or the over temperature will kick out the electrical element and you will discover it when the wife is in the shower.The pop off valve is not the standard size and I could only find them at Atwood.IMHO The Liberty designed system is much simpler,with less opportunity for failure.