Patent ID: 7077155

Claim:
A hot water on demand system for a household comprising: a hot water heater having an inlet and an outlet port; a hot water line coupled to the outlet port of the hot water heater and at least one plumbing fixture for circulating hot water from the hot water heater to each plumbing fixture; a cold water line coupled to each plumbing fixture for circulating cold water to each plumbing fixture; a hot water return line coupled to the hot water line adjacent each plumbing fixture and to an inlet of the hot water heater; a first check valve coupled to the hot water return line and the cold water line for regulating flow from the cold water line to the inlet port and for preventing hot water entering the cold water line; a second check valve coupled to the hot water return line between the inlet port and each plumbing fixture for preventing pressure reduction in the hot water return line below a predetermined level and thereby preventing cold water from entering the hot water return line; a pump means coupled to the hot water return line for circulating hot water from each fixture to the inlet port of the hot water heater.