"misia" wrote in message
ail.from.there...

I agree electric heater might be the most energy hungry element,
especially if
the water has to be retained and temperature maintained in the tank for 10
people onboard.

This is something that I'm considering to built around hybrid solution.

I came accross this Webasto heater:

http://www.navstore.com/pdf/webasto/Webasto%20TSL17.pdf

What do you think?

I did not check your link, but what you might want to ask your engineer for
would be a design for a water-to-water (Glycol based)heat exchanger to keep
your shower water HOT. This could be done with off-the-shelf electric
components if you have the space, and need only be configured to your space
by your architect and engineer. The electric would be your seldom-used
backup, and you could have your choice of 120, 240, or custom voltage
standard mount heating elements (check off-the-grid, solar, and wind power
resources for these items).

Rob
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