Abstract: According to the present invention, a gas-air mixing device used in a gas boiler includes: a gas supply tube branched into a first gas flow path and a second gas flow path; an air supply tube branched into a first air flow path and a second air flow path by means of an air-flow-path branching apparatus; a pressure valve which is connected to the inlet side of the gas supply tube in order to adjust the supply rate of gas being supplied to the gas supply tube; and a drive unit in which two valve bodies are connected to a rod that moves vertically up and down due to the magnetic force of an electromagnet; and the air-flow-path branching apparatus is formed to have a slot that connects to either the first air flow path or the second air flow path, and has a joining part which the rod can pass through in a position corresponding to the slot.

Abstract: The present invention relates to a structure for controlling a temperature of hot-water supply from a waste heat recovery system, and more particularly, to a structure for controlling a temperature of hot-water supply from a waste heat recovery system using a three-way valve capable of stably supplying hot water at a hot-water supply setting temperature during hot-water supply use using the three-way valve and saving energy to improve system efficiency, in a waste heat recovery system recycling waste heat.

Abstract: The purpose of the present invention is to provide a combustion device for improving a turndown ratio, which is capable of stably implementing a combusted state in a low-output load region by improving a turndown ratio of a burner. To this end, the present invention provides the combustion device having a premixing chamber (300) which is connected to an air supply tube (100) and a gas supply tube (200), and which has a space for premixing air and gas provided therein, wherein the space for premixing the air and gas supplied from the air supply tube (100) and the gas supply tube (200) is divided into multiple stages of a venturi structure in the premixing chamber (300), and the discharging direction of the gas discharged inside the premixing chamber (300) through the gas supply tube (200) is formed in parallel to the flow direction of the gas supplied inside the premixing chamber (300) through the air supply tube (100).

Abstract: According to the present invention, a gas-air mixing device used in a gas boiler includes: a gas supply tube branched into a first gas flow path and a second gas flow path; an air supply tube branched into a first air flow path and a second air flow path by means of an air-flow-path branching apparatus; a pressure valve which is connected to the inlet side of the gas supply tube in order to adjust the supply rate of gas being supplied to the gas supply tube; and a drive unit in which two valve bodies are connected to a rod that moves vertically up and down due to the magnetic force of an electromagnet; and the air-flow-path branching apparatus is formed to have a slot that connects to either the first air flow path or the second air flow path, and has a joining part which the rod can pass through in a position corresponding to the slot.