This system was installed in an Eagle Lake Cottage just NE of Kingston, Ontario in a cottage owned by a UCLA Physics Professor who already had a pressurized lake water feed into his cottage.
Since the heater is a non-pressurized system, the cold water pressure had to be removed before the water flows to the heater.
In the installation pictured, this is done by feeding the pressurized water into a small plastic holding tank sitting on a wooden "saddle" on the hot water tank and water flow to this tank is controlled with a "toilet tank" float valve. Water is gravity fed into the system as needed.
Pressure is added to the hot water line after it leaves the water heater using a small 3 1/2 gpm pump controlled with a 3/4 liter pressure tank installed in the hot water supply line before the first tap. It cycles off at 40 lb pressure and on at 20 lb to deliver water pressure to any tap similar to a conventional system in your house. This small DC pump and pressure tank is similat to those found in cabin cruisers or house trailers.