Flow control valve and hot-water type heater apparatus employing the same

摘要

To be able to control minute flow in a heat exchanger flow control valve without requiring a minute opening portion, an opening surface area of a hot-water inlet pipe 19 into which hot water flows from an engine 1 is restricted by a control passage 17a provided in a needle valve 17 of a flow control valve 4, and along with this, an opening surface area of a hot-water outlet pipe 20 connected to an inlet side of a heat exchanger for heater use 3 is restricted by a control passage 17b formed in the needle valve 17, and a middle portion A of these two control passages 17a and 17b is constantly connected to a bypass circuit 5. Pressure of the middle portion thereof can thereby be lowered, pressure applied to the heat exchanger 3 can be adequately reduced, and for this reason minute flow through the valve 17 can be controlled even without establishing a minute opening portion using the needle valve 17.