Abstract: The server may be configured to: estimate a total number of the new replaceable components to be purchased by the user of the device at the predetermined timing that is before the replacement timing; based on the estimated total number of the new replaceable components to be purchased and based on a stock quantity of the replaceable components at the predetermined timing, calculate a quantity of stock shortage of the replaceable components at the predetermined timing; and generate replenishment information for replenishing stock of the replaceable components according to the calculated quantity of stock shortage of the replaceable components.

Abstract: A safety circuit 31, which compulsorily closes an on-off valve for supplying a gas to a burner when a microcomputer for performing a combustion control is in an abnormal condition, does not operate unless abnormality occurs to the microcomputer 1, and therefore even when the safety circuit 31 is out of order, an ignition operation is performed as it is. A transistor 4 is not turned off until a fixed time elapses from a start of an ignition sequence in the safety circuit 31, but the fixed time is shortened by a timer acceleration circuit 32, and if the transistor 4 is turned off by a transistor 2 being turned on, the safety circuit 31 is determined as normal, so that the normal ignition sequence is executed thereafter.

Abstract: A safety circuit 31, which compulsorily closes an on-off valve for supplying a gas to a burner when a microcomputer for performing a combustion control is in an abnormal condition, does not operate unless abnormality occurs to the microcomputer 1, and therefore even when the safety circuit 31 is out of order, an ignition operation is performed as it is. A transistor 4 is not turned off until a fixed time elapses from a start of an ignition sequence in the safety circuit 31, but the fixed time is shortened by a timer acceleration circuit 32, and if the transistor 4 is turned off by a transistor 2 being turned on, the safety circuit 31 is determined as normal, so that the normal ignition sequence is executed thereafter.