COMBUSTION AMOUNT-VARYING DEVICE

PROBLEM TO BE SOLVED: To reliably prevent the occurrence of pulsation combustion due to a pressure fluctuation in a return oil pipe by a method wherein an accumulator for buffering pressure and a check valve are located in the return oil pipe situated upper stream from a flow rate regulating valve, used in a combustion amount-varying device used in a petroleum hot water supply apparatus for domestic use, in a state that the check valve is positioned on the nozzle side. SOLUTION: In a forward backward movement force regulating mechanism 60 formed such that by contacting and separating a valve element support ring, fitted in the tip of a valve element forward backward movement rod 47, and a spherical valve body 45 with and from a valve seat 44, an amount of return oil flowing through a return oil pipe is regulated, a forward backward movement force regulating mechanism 60 is provided to regulate the forward and backward force of a valve element forward backward movement rod 47. This mechanism is arranged to regulate a force to partition the spherical valve element 45 from a valve seat 44 through rotation of a screw lever 62. Further, an accumulator AL is arranged at the return oil pipe situated upper stream from a flow rate regulating valve, and the accumulator AL is formed such that a piston 81 is arranged in a casing 80. This constitution absorbs the change of a pressure on the secondary side and prevents the occurrence of a change of a spray amount due to a change of a pressure on the secondary side.