A fan includes: an impeller including a main plate having a first plane, a plurality of first blades each formed the first plane, and a shroud formed integrally with the plurality of first blades; a fan case; a drive source; and a rotation shaft. The first blades each include a linearly protruding region that is linearly increased in height from an outer circumferential side to an inner circumferential side, and a curvedly protruding region that is curvedly increased in height from the outer circumferential side to the inner circumferential side, the height extending in a direction in which each first blade protrudes. The linearly protruding region is welded to the main plate. Accordingly, a highly durable fan can be implemented that allows sufficient durability to be maintained even under a high temperature environment or an acid environment.

A vent proving system is described for use with a gas fired appliance. The gas fired appliance includes a gas burner, a vent damper for selectively opening or closing an exhaust vent from the gas fired appliance and a relay control for operatively controlling the vent damper and the gas burner to open the damper if the gas burner is on. The vent proving system comprises a sensor for sensing a variable in the vent representing air flow direction in the vent. An electrical switch is connected in series between the relay control and the vent damper. A controller is operatively connected to the sensor, the electrical switch and to the relay control.

A water heater includes: a burner; a heat exchanger; a fan for supplying air to the burner and emitting combustion gas having passed through the heat exchanger to outside of the water heater; and a drainage water discharge path connected to the heat exchanger. The drainage water discharge path has a water-sealing structure that is water-sealed by drainage water. The water heater further includes a control unit: having a water-seal determination unit giving permission that the water heater can operate in a normal mode based on a condition that the drainage water discharge path has been water-sealed; and issuing an instruction to cause the burner to intermittently operate for a time period until the water-seal determination unit gives the permission.

A water heater system includes a tank for storing water; a flue assembly positioned within the tank, the flue assembly adapted to transfer heat from flue gases within the flue assembly to water in the tank; a burner in fluid communication with an inlet end of the flue assembly and operable in at least a high input mode and a low input mode to deliver the flue gases to the flue assembly, the exhaust assembly having a threshold temperature above which the exhaust assembly is not suitable; and an exhaust assembly including a fan, wherein at least in the low input mode, the flue gases condense in the flue assembly, and wherein operation of the fan reduces a temperature of the flue gases in the exhaust assembly to below the threshold temperature at least in the high input mode.

A plurality of water heaters are connected in parallel with respect to a hot water supply path, and each of the plurality of water heaters has an exhaust path connected to an exhaust path assembly. Each of a plurality of sensing units is configured to be shifted from an electrically conducting state to an electrically non-conducting state when each of the plurality of sensing units senses an abnormal condition about air supply or exhaust. A series circuit of the plurality of sensing units is electrically connected in series to a resistance element between the power supply line and the ground line. The controller is configured to monitor an abnormal condition about air supply or exhaust based on a voltage on a node between the series circuit and the resistance element.

The embodiments of the present application disclose a combustion control system of a gas water heater or wall-hanging boiler, and a control method thereof. The system comprises: a flue gas channel consisted of a combustor, a heat exchanger and a stepless speed regulating fan and a smoke tube, which are connected sequentially; a control unit connected to a signal input end of the stepless speed regulating fan; a wind pressure sensor assembly that detects a pressure signal upstream of an impeller of the stepless speed regulating fan, a signal output end of the wind pressure sensor assembly being connected to the control unit; the control unit comprising a storage for storing a correspondence relationship between the pressure signal upstream of the stepless speed regulating fan and a thermal load of the combustor, and a controller that controls operation of the stepless speed regulating fan according to the correspondence relationship. The present application further regulates the rotational speed of the stepless speed regulating fan by detecting the pressure signal upstream of the impeller of the stepless speed regulating fan, thereby achieving a better wind-resistant performance of the present application.

A water heater includes a case, and a water line disposed within the case. The water line extends between an inlet and an outlet, and a heat exchanger is disposed in the case on the water line. A burner is disposed in the case, and a controller is also disposed in the case. A flue is coupled to the case. The flue defines an exhaust outlet contiguous with external air. The flue includes a temperature sensor, a fan, and a plate disposed within the flue. The plate is configured to rotate within the flue between an open position and a closed position. Also included in the case is a heating element coupled to the water line between the inlet and the outlet of the water line. The controller is in signal communication with the temperature sensor and the fan, and the controller is in operative communication with the heating element.

A controller is configured to set total stop in which operations of all of a plurality of water heaters are stopped when an abnormal condition of a fan or an abnormal condition in communication is sensed in any of the plurality of water heaters while at least one of the plurality of water heaters is operating. The controller is further configured not to set total stop when an abnormal condition of the fan or an abnormal condition in communication is sensed in at least one of the plurality of water heaters while a sensing element for sensing a backflow of an exhaust from an exhaust path assembly is connected to the controller.

Aspects of the invention provide a heat exchanger including a shell at least partially defining an interior region; a burner positioned to deliver combustion gases into the interior region; and a plurality of tubes configured to circulate water therein, the plurality of tubes extending through the interior region. The plurality of tubes further including an inner set of tubes and an outer set of tubes, the inner set of tubes being closer to the burner than the outer set of tubes. The inner set of tubes and the outer set of tubes being positioned adjacent to one another such that the outer set of tubes is staggered from the inner set of tubes and tubes of the outer set of tubes are adjacent to tubes of the inner set of tubes. Additionally, baffle segments are annularly positioned in the interior region adjacent the plurality of tubes. Adjacent baffle segments defining gaps for the flow of the combustion gases.

A water heater capable of cooling a fan by inflow of air while suppressing backflow of combustion gas is provided. A fan includes: a fan case having a back surface wall; an impeller having a first blade and a second blade and housed in the fan case; a drive source rotating the impeller; and a rotation shaft coupling the impeller and the drive source through a through hole provided in the back surface wall. A gap through which air outside the fan case is suctioned into the fan case is provided between the rotation shaft and the back surface wall. The second blade faces the back surface wall without another member interposed therebetween throughout a range from an inner circumferential side to an outer circumferential side of the second plane.