Originally Posted by Saltaire1012
With respect to what water heater to use, for a raw water cooled engine I'm going to use a 6 gallon ISOTEMP which is all stainless construction and riuns around $700. More expensive then some others but should have a longer life than any that do not have stainless cold throughwhich the raw water passes. An additional advantage ofthe ISOTEMP is that it can be mounted in various ways even to a bulkhead.
I think you are missing my point. The max raw water cooling water should be around 165 F and fresh water systems commonly run around 190 F. So there is a lot more heat available in a fresh water system.
The raw water heat will work fine on a long motor, but will require a substantial run time if you are thinking about running the engine for a bit to heat up some water.
As far as the ISOTEMP goes they are great units, I wish there was one in my boat.