Water Heating System Schematic

The solar water heating system is composed of two sub-systems that interact within the heat exchanger.  The first system consists of the utility water that is heated in the thermo siphon passes through a ½ inch diameter copper heating coil and back through the thermo siphon.  A two gallon insulated tank is used as the supply for the circulation pump.  A Shurflo series 2088 diaphragm pump (12V DC) circulates water at 2.7 gpm against a 3 psi head through the inlet at the base of the thermo siphon.  The sun radiates heat to the black surface of the copper plate within the thermo siphon.  The plate has a surface area of 32 ft².  The utility water passes through the copper plate and is warmed through convection heat transfer. The outlet of the thermo siphon is plumbed to the ½ in ID copper heating coil located within a 20 gallon hot water storage tank.  The outlet of the heating coil is plumbed back to the supply tank.  The supply allows for variations in the water volume and also creates an access point to fill and drain the system.  The water in this system never contacts the drinking water and is only used to heat the drinking water.

Hot/Cold Water Storage and Faucet



The drinking water system consists of a 5 gallon cold water tank and a 20 gallon hot water tank both of which are constructed from HDPE.  Water delivery to the faucet is accomplished by 1/2" flexible copper piping.  When water is used the cold water tank is filled by a Shur Flo 8000 pump.  The hot water tank refill valve regulates the flow of refill water from the cold water tank to the hot water tank.  All flow in the system is gravity driven except for recharge of the cold water tank.







Water Purification Process

In order for water to be drinkable, it must be free of sediments and bacteria.  The water is passed through a two stage sediment filter.  The first stage is a 20-50 micron cartridge filter.  The second stage is a 5-15 micron cartridge filter.  After sediment is removed the bacterium and viruses must be removed from water before it is drinkable.  This accomplished by passing it though a UV Filter that kills 99.9% of all bacteria.  The PurGuard UV filter uses 103.8 watts and 120V AC.  The pressure drop across this filter is negligible due to the high cross section area.  The filters will be placed between the rain water storage tank and the cold water storage tank.  The pump used to drive the flow from the rain water tank through the filters to the cold water storage tank is a Shurflo series 8000 diaphragm pump.

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