Abstract: A hot water supply device 1 includes a fin-and-tube type heat exchanger (21) that applies heat to fresh water with combustion gases, and a heat exchanger casing (22) for housing the heat exchanger (21), and in order to be able reliably to determine by a simple method whether the hot water supply device is clogged by lime scale, there are provided a temperature detector (31) for detecting the surface temperature of the heat exchanger casing (22) and a control unit (7) that determines that scale has built up in the heat exchange tubing (27) of the heat exchanger (21) when the temperature detected by this temperature detector (31) is greater than a set temperature.

Abstract: A hot water supply device (1) includes: a fin and tube type heat exchanger (17) for aplying heat to water with combustion gas; a temperature detection means (32) for detecting an exhaust temperature after heat exchange by the heat exchanger (17); and a determination means that determines that scale is deposited within the heat exchange tubing (27) of the heat exchanger (17) if the exhaust temperature detected by the temperature detection means (32) is higher than a set temperature.

Abstract: According to the required amount of heating, a controller of a combustion apparatus exercises selective on-off switching control on capacity control switching valves for the supplying of gas to three different combustion areas partitioned respectively by a group of three combustion burners, a group of five combustion burners and a group of nine combustion burners, whereby the three combustion areas can selectively be burned, thereby the combustion capacity is changed and switched to any of a plurality of combustion capacity levels. A combustion exhaust temperature sensor is disposed in the vicinity of the inlet of an exhaust stack. Judgment temperatures corresponding respectively to combustion capacity levels for combustion exhaust high-temperature abnormality judgment are set.

Abstract: A hot water supply device 1 includes a fin-and-tube type heat exchanger (b 21) that applies heat to fresh water with combustion gases, and a heat exchanger casing (b 22) for housing the heat exchanger (b 21), and in order to be able reliably to determine by a simple method whether the hot water supply device is clogged by lime scale, there are provided a temperature detector (b 31) for detecting the surface temperature of the heat exchanger casing (b 22) and a control unit (b 7) that determines that scale has built up in the heat exchange tubing (b 27) of the heat exchanger (b 21) when the temperature detected by this temperature detector (b 31) is greater than a set temperature.

Abstract: According to the required amount of heating, a controller of a combustion apparatus exercises selective on-off switching control on capacity control switching valves for the supplying of gas to three different combustion areas partitioned respectively by a group of three combustion burners, a group of five combustion burners and a group of nine combustion burners, whereby the three combustion areas can selectively be burned, thereby the combustion capacity is changed and switched to any of a plurality of combustion capacity levels. A combustion exhaust temperature sensor is disposed in the vicinity of the inlet of an exhaust stack. Judgment temperatures corresponding respectively to combustion capacity levels for combustion exhaust high-temperature abnormality judgment are set.