-Aluminum water heaters do not exist on land...... Think about it.
-Glass lined steel tanks are the cheapest of the cheap construction for land based water heaters.
-SS water heaters are the premium product often yielding a lifetime pressure vessel warranty on land tanks. The Isotemps are both a SS pressure vessel and SS coil/hx and they include a thermostatic mixing valve and it is now a requirement to temper your marine engine heated water heater!
Disclaimer: Right out of college I worked as a manufacturers rep in the hydronics industry selling boilers, baseboard, radiant heat, water heaters, air handlers, control systems etc.. etc.. As such I have a good handle on the water heater market, how they are made, and lots of good data on RMA's and warranty claims, as I was the factory representative doing them.
My dad was one of the first people to install, at the time, one of the new
Super-Stor prototype indirect fired water heaters on our homes heating system back in 1976 or so. Heat Transfer Products, the makers of that tank, used to build a miniature version for boats before pulling out of the market last year.
If I remember correctly it was the first SS pressure vessel water heater in the US market.
I have not ever replaced a marine Super-Stor.... I replace boat-loads of Raritan and all the "square" aluminum tanks. I have replaced one Isotemp due to a factory defect
, and they stood behind it very, very well. I have never replaced one to corrosion or rust however. A premium SS tank will last longer, not require an anode, and will not rust through....
That Super-Stor tank in my mothers house is a SS tank with a cupronickel HX. That water heater is still in perfect operation today 39 years later...!!! My mothers other house has been through 8 or 9 glass lined water heaters in the same time frame.
You do get what you pay for... The idea in the marine industry
is a premium product
gives me a HUGE chuckle.