Abstract: Disclosed is a two-way check/bypass valve assembly connected between the hot and cold-water standpipes under the sink that allows convective circulation of hot water from an existing water heater, through the existing hot water distribution pipes, through the valve assembly to the cold water standpipe, through the existing cold water standpipe and distribution pipes, and back into the water heater. The convective water flow is induced by the temperature difference between the hot water in the pipe rising above the water heater, and the slightly cooled, and denser, water flowing back down into the water heater. The valve will allow this low circulation water flow so long as both hot and cold faucets at the outlet are closed, and will prevent any cross flow between the hot and cold pipes under the sink when either the hot or cold faucet is opened.

Abstract: Disclosed is a two-way check/bypass valve assembly connected between the hot and cold-water standpipes under the sink that allows convective circulation of hot water from an existing water heater, through the existing hot water distribution pipes, through the valve assembly to the cold water standpipe, through the existing cold water standpipe and distribution pipes, and back into the water heater. The convective water flow is induced by the temperature difference between the hot water in the pipe rising above the water heater, and the slightly cooled, and denser, water flowing back down into the water heater. The valve will allow this low circulation water flow so long as both hot and cold faucets at the outlet are closed, and will prevent any cross flow between the hot and cold pipes under the sink when either the hot or cold faucet is opened.

Abstract: A two-way check/bypass valve is connected between the hot and cold water supply lines at hot and cold water faucets located most distantly from the water heater in a building. The valve establishes and maintains convective hot water circulation at a low flow rate from the heater to the most distant hot water faucet, through the cold water supply line, and back to the heater, during the period of time when the hot and cold water faucets are closed. When the hot water faucet is opened, hot water is nearly instantly available. Convective hot water circulation is stopped by the valve when either the hot or cold faucet is opened. The valve also prevents mixing of hot and cold water when either the hot or cold faucet is open and includes provision for dampening any water hammer effect.

Abstract: A water heater unit is described for providing convective water flow through a water circulatory system. In one embodiment, the water heater unit has an outer housing, a water tank disposed within the housing, and a first cold water inlet coupled to the tank and connectable to a cold water supply line. A hot water outlet is coupled to the tank and connectable to a hot water supply line. A connection chamber adjacent to the tank has a second cold water inlet connectable to the cold water line, and a chamber outlet connected to the first cold water inlet of the tank. The connection chamber has at least one return inlet connectable to the hot water return line at a position to allow a substantially continuous flow of return hot water driven by convection forces without the benefit of a recirculation pump.

Abstract: This invention consists of a heat exchanger, a heating element, and a return line from a remote faucet to provide a constant circulatory flow of hot water through hot water distribution lines in a building utilizing a tankless water heater, such that hot water is available instantly at remote faucets in the building. The invention will eliminate the waste of water and heat while waiting for hot water to arrive at the outlets. A second benefit is to heat the mass of cold water known as the cold sandwich that results from the time delay for the heating element in the tankless heater to achieve its operating temperature. A third benefit is the convenience of not having to wait for hot water to arrive at remote faucets.

Abstract: A water heater unit is described for providing convective water flow through a water circulatory system. In one embodiment, the water heater unit has an outer housing, a water tank disposed within the housing, and a first cold water inlet coupled to the tank and connectable to a cold water supply line. A hot water outlet is coupled to the tank and connectable to a hot water supply line. A connection chamber adjacent to the tank has a second cold water inlet connectable to the cold water line, and a chamber outlet connected to the first cold water inlet of the tank. The connection chamber has at least one return inlet connectable to the hot water return line at a position to allow a substantially continuous flow of return hot water driven by convection forces without the benefit of a recirculation pump.

Abstract: An integral water circulation device reliably provides rapid hot water at remote hot water faucets throughout a building by creating a low rate convective circulatory flow from the building water heater through a return line and the circulation device itself, without mixing hot and cold water within the system.

Abstract: An integral water circulation apparatus supplies instant hot water at hot water faucets remotely located from the building water heater through a convective circulation flow of hot water from the water heater It is therefore simpler in design, less expensive to install, and more reliable than the more complex prior art systems.

Abstract: A water circulation apparatus to provide instant hot water to faucets remote from the heater in residential and small commercial buildings when water is periodically used in the building. The apparatus comprises a body containing an aspirator and a check valve, and provisions for installation in the water supply line to the heater and cold water faucets. It uses a small water return line from a tee installed in the hot water pipe near the remote faucet, to a connector on the water circulation unit, thereby establishing a circulation loop from the water heater, through the hot water pipe, the tee and return line, and through the water circulation unit back to the heater. The aspirator is a tapered bore in the body with a concentric nozzle positioned in the large end, and a low pressure tap located in the vicinity of the nozzle outlet. The check valve uses a neutrally buoyant poppet to minimize friction.

Abstract: A dual mode water circulation apparatus to provide instantaneous hot water to faucets remote from the heater in residential or small commercial building water systems. The apparatus comprises a cold water heat exchanger, a high sensitivity check valve, and an aspirator incorporated into a single unit.The heat exchanger is a chamber installed in the cold water supply line, containing a cooling tube exposed to the water. The check valve has a neutral buoyancy poppet and closes against an angular seat. The aspirator has a reduced cross section nozzle inside a tapered chamber connected to the water supply pipe, with a low pressure tap in the chamber bore.The apparatus is installed at an angle to the horizontal. The cooling tube is connected to a water return line from a tee in the hot water pipe at the remote faucet. The water circulation loop is from the remote hot water faucet to the heat exchanger portion of the apparatus, to the check valve, then to the aspirator and into the cold water supply to the heater.