Hydrothermal stabilizer and expansion tank system

A hot water recovery and expansion system comprising:

• a hot water tank having a water inlet and a hot water outlet;
• a hot water delivery line connected said hot water outlet and at least one plumbing fixture;
• a cold water delivery line connected between said plumbing fixture and a cold water source;
• crossover pipe means, connected between said hot and cold water delivery lines, for enabling cold water to flow from the cold water delivery line into the hot water delivery line, said crossover pipe being disposed at a point remote from said hot water source;
• tank means for containing water, said tank means having a top with a water inlet therein connected to the cold water source and a bottom with a water outlet therein connected to the hot water tank inlet;
• a buoyant piston having an air volume therein, and said piston being movably disposed within said tank means and having a perimeter slidably engaging an inside wall of said tank means, said buoyant piston including;
• means for enabling water entering the water inlet to pass by the buoyant piston when the buoyant piston is displaced to a selected lower position in said tank means by the entering water, said buoyant piston having sufficient buoyancy to rise to the tank means top from the selected lower position when water is not entering the tank means water inlet and draw hot water from the hot water source and hot water delivery line into the tank means below the buoyant piston, water from the hot water delivery line being supplied through the crossover pipe from the cold water delivery line;
• and
• means, disposed within the buoyant piston, for controlling increases in water pressure due to thermal expansion of water in the tank means.

Plumbing apparatus for reducing energy consumption of a hot water heater, said plumbing apparatus comprising:

• tank means for containing water, said tank means having a top with a water inlet therein and a bottom with a water outlet therein;
• a buoyant piston having an air volume therein, and said piston being movably disposed within said tank means and having a perimeter slidably engaging an inside wall of said tank means;
• means for enabling water entering the water inlet to pass by the buoyant piston when the buoyant piston is displaced to a selected lower position in said tank means by the entering water, said buoyant piston having sufficient buoyancy to rise to the tank means top from the selected lower position when water is not entering the tank means water inlet;
• and
• means, disposed within the buoyant piston, for preventing rupture of the tank means due to thermal expansion of water within the tank means.

A hot water recovery and expansion system comprising:

• a hot water heater having a water inlet and a water outlet;
• a hot water delivery line connected between said hot water heater and at least one plumbing fixture;
• a cold water delivery line connection between said plumbing fixture and a cold water source;
• pump means, interconnected between said hot and cold water delivery lines, for circulation of water from the hot water delivery line through the cold water delivery line and into the hot water heater;
• control means for causing the pump means to circulate water from the hot water line into the cold water line proximate said plumbing fixture and back to the hot water heater when a hot water valve on said plumbing fixture is turned on;
• temperature sensor means, connected to control means, for causing said control means to stop the pump means to prevent heated water from being circulated through the cold water delivery line;
• tank means for containing water, said tank means having a top with a water inlet therein connected to the cold water source and a bottom with a water outlet therein connected to the hot water heater inlet;
• a buoyant piston having an air volume therein, and said piston being movably disposed within said tank means and having a perimeter slidably engaging an inside wall of said tank means;
• means for enabling water entering the tank means water inlet to pass by the buoyant piston when the buoyant piston is displaced to a selected lower position in said tank means by the entering water, said buoyant piston having sufficient buoyancy to rise to the tank means top from the selected lower position when water is not entering the tank means water inlet;
• and
• means, disposed within the buoyant piston, for controlling increases in water pressure due to thermal expansion of water in the tank means.