Passive injection system used to establish a secondary system temperature from a primary system at a different temperature

摘要

A passive injection system for a hydronic heating system having a primary loop and a secondary loop is described. The passive injection system establishes a secondary temperature in the secondary loop significantly different from the temperature of the primary or boiler loop. A Venturi tee passively induces flow from the primary loop to the secondary loop. A valve is provided in the flow path of the Venturi tee between the primary and secondary loops and allows some flow or no flow from the primary loop to enter and mix with the secondary loop, depending upon whether the valve is open, closed, or partially open. A return leg is provided at a tee connection for returning flow from the secondary loop to the primary loop. In this way, the temperature of the secondary loop can be set well below the temperature of the primary loop and can be controlled without changing the flow rate of the secondary loop.