Hot water circulation apparatus with adjustable venturi

A dual mode water circulation apparatus for installation in a water supply line in a building upstream of a water heater to provide continuously heated water to one or more remote hot water faucets served by a common hot water pipe, the apparatus being connected in a water return loop that includes a portion of the water supply line that is downstream of the apparatus, the water heater, the common hot water pipe, and a return line from a remote faucet,

• said apparatus including a housing having a first inlet for connection to the water return line, an outlet for connection to that portion of the water supply line that connects to the water heater, and a second inlet for connection to the water supply, a chamber in said housing with said inlets and outlet connecting to said chamber, a check valve between said first inlet and said chamber preventing flow from said apparatus outwardly from said first inlet, a venturi in said chamber to cause reduced pressure adjacent said first inlet to cause an increase in flow in said water return loop when water flows into said apparatus from said water supply pipe, and a variable capacity bypass connected about said venturi and between said second inlet and said outlet to control water pressure at said first inlet and thus the flow of water in said water return loop, said bypass including a water conduit connected between said second inlet and said outlet, a check valve in said conduit and yielding means urging said check valve toward a conduit closing position.