Dual heat exchange mode water heating system for boats

A supplemental water heating kit for use with an existing hot water tank of a boat through communication with a coolant line from an engine of the boat, the hot water tank having a cold water inlet and a hot water outlet and an engine coolant conduit running through the hot water tank connected with the coolant line for the engine to heat water in the hot water tank, the kit comprising:

• (A) a heat exchanger adapted to be positioned externally of the hot water tank, the heat exchanger including an exchanger water inlet and an exchanger water outlet with a first flow path extending from the exchanger water inlet to the exchanger water outlet for fluid connection between the cold-water inlet and the hot water outlet of the hot water tank and a coolant inlet and an coolant outlet with a second flow path extending from the coolant inlet to the coolant outlet for fluid connection with the coolant line for the engine of the boat;
• (B) a water pump for connection in fluid communication between the hot water tank and the exchanger water inlet of the heat exchanger;
• (C) a water outlet line for the heat exchanger for fluid connection between the exchanger water outlet of the heat exchanger and the hot water tank to enable heated water from the heat exchanger to be circulated from the first flow path of the heat exchanger back into the hot water tank;
• (D) a water inlet line for the heat exchanger for connecting the hot water tank and the exchanger water inlet of the heat exchanger to supply water from the hot water tank to the heat exchanger;
• (E) a coolant inlet line for fluid connection between the coolant line of the engine and the coolant inlet of the heat exchanger for supplying heated coolant from the coolant line of the engine to the second flow path of the heat exchanger;
• and
• (F) a coolant outlet line for fluid connection between the coolant outlet of the heat exchanger and the coolant line of the engine to provide a flow of coolant from the second flow path of the heat exchanger into the coolant line of the engine;
• wherein the pump circulates water from the hot water tank through the first flow path of the heat exchanger as heated engine coolant is circulated through the second flow path of the heat exchanger to effect heat transfer from the heated engine coolant to the water circulating through the first flow path.

A water heating system for use with a boat having a boat engine with a coolant line for the engine comprising:

• (A) a hot water tank for containing a supply of heated water;
• (B) a cold water source line connected with the hot water tank for supplying water to the hot water tank;
• (C) a hot water supply line connected with the hot water tank for providing an outlet source of hot water from the hot water tank;
• (D) a heat exchanger for transferring heat from heated engine coolant running through the coolant line of the engine to water from the hot water tank, the heat exchanger having a.first flow path in fluid connection with the hot water tank to provide a circulation of water to and from the hot water tank and a second flow path in fluid connection with the coolant line to provide a circulation of heated coolant to and from the heat exchanger;
• and
• (E) a pump in fluid communication with the hot water tank and the first flow path of the heat exchanger to pump water in circulation between the first flow path of the heat exchanger and the hot water tank.

A water heating system for use with a boat engine having a coolant line operable in an active heating mode and a passive heating mode, comprising:

• (A) a hot water tank containing a supply of water;
• (B) a heat exchanger external of the hot water tank;
• (C) a first flow path in the heat exchanger in fluid connection with the hot water tank to permit circulation of water between the heat exchanger and the hot water tank;
• and
• (D) a second flow path in the heat exchanger in fluid connection with the coolant line for the boat engine to permit circulation of engine coolant between the heat exchanger and the coolant line;
• so that during operation in the active heating mode, water is circulated between the hot water tank and the heat exchanger as engine coolant is circulated between the coolant line and the heat exchanger to effect heat transfer from the engine coolant to the water, and during operation in the passive heating mode, circulation of water through the heat exchanger is stopped so that water remains in the hot water tank.

A method for heating fresh water on a boat, comprising the steps of:

• (A) running a boat engine to generate heat in the engine;
• (B) supplying water to a hot water tank;
• (C) providing a heat exchanger external to the hot water tank;
• (D) circulating water between the hot water tank and the heat exchanger;
• and
• (E) cycling a coolant from the engine through a coolant line that passes through the hot water tank to transfer heat to water in the hot water tank and through the heat exchanger to transfer heat to the water circulating through the heat exchanger.

A water heating system for use with a boat having a boat engine with a coolant line for the engine comprising:

• (A) a hot water tank for containing a supply of water to be heated;
• (B) a cold water source inlet for the hot water tank for enabling water to be supplied to the hot water tank;
• (C) a hot water supply outlet for the hot water tank for providing an outlet source of hot water from the hot water tank;
• (D) a heat exchanger for transferring heat from heated engine coolant running through a coolant line of the engine to water to be heated in the hot water tank, the heat exchanger having a first flow path in fluid communication with water in the hot water tank to circulate the water through the heat exchanger and a second flow path in fluid communication with the coolant line to provide a circulation of heated coolant through the heat exchanger;
• and
• (E) a pump in fluid communication with the hot water tank and the first flow path of the heat exchanger to pump water in circulation between the first flow path of the heat exchanger and the hot water tank.