[prairieschooner]

Yes, The RARITAN Water Heater is expensive but there is another alternative!
1st the RARITAN is most likely better constructed and does have a Sacrificial Anode. If the Anode is replaced at the recommended intervals, this Water Heater may actually outlast most other items on the coach. The problem is that most people do not replace the anode and then the Tubes will fail due to Corrosion.
I chose a SEAWARD Water Heater. It is a rectangular shape and has the stainless steel sheet metal cover (optional). The problem is that it has a smaller tank (11 gallons) if that matters, still we haven't run out of Hot Water. I like it better for Boondocking because it does help to limit Water use, I also use a smaller Water Pump than the Coach came with.

Here is a link to one of the suppliers, you'll see that the RARITAN is about twice the price;

http://www.westmarine.com/webapp/wcs...SiteSearchView