Hi All:

Currently going through a total home renovation of a 2 story house in Hawaii. 1st and 2nd floor each has 2 bath and 1 kitchen, so entire house has 4 baths, and 2 kitchens. Total of 4 adults, and 2 young children. Rectangular house layout, with all fixtures on one long side, bunched up in the middle. My dilemma is regarding the hot water heater (HWH) and hot water pipe runs. I will be getting an active/open-loop direct solar hot water heating system with a 120 gal tank with electric backup, which is pretty standard here. See "Direct" system for diagram:

http://www.unitedsolar.net/solar-power-merritt-island-solar-water-heaters.php

My desire is to get the hot water runs as short as possible and there is a location that will be ideal as far as the shortest distances to all the fixtures. However, that location is not ideal as far as ascetics goes and will not support a 120 gal tank without impeding the 1st floor kitchen window because of the tank width. The existing HWH location is ideal as far as getting the HWH tucked out of the way but adds to the pipe run distance as it's located on one side of all the fixtures.

The 2 options I can think of are:

1) Get the plumber to install a hot water return line from the existing HWH location to the farthest fixture and have a recirc hot water system. Either on-demand or timed operated or both.

2) Install a dual tank system, 120gal storage tank only at the existing location (collect hot water from panels), and a skinny ~25 gal tank at the non-ideal location with electric backup.

The reason I am not jumping at the #1 option is due to the additional cost to install the return line. Code will require to insulate the hot water lines for a recirc system? Keep in mind, I am in Hawaii and EVERYTHING is very expensive, especially in the construction industry, and this will definitely not be a typical install, for either options in my neck of the woods. Just to give you an idea how expensive things are here, we pay $0.35/KWH for electricity.

Sorry this came out really long. Your suggestions/comments are much appreciated.

Thanks!!