A vent attachment facilitates attaching a coaxial air intake and exhaust vent of a tankless water heater to a Category I vent, such as B-vent. The vent attachment comprises a first end with a coaxial connector comprising a central exhaust pathway and a circumferential air intake pathway. The vent attachment also comprises a second end with a tubular exhaust vent connector in fluid communication with the central exhaust pathway. The vent attachment further comprises a frame that encloses the central exhaust pathway and comprises a mesh configured to provide fluid communication through the frame with the air intake pathway. Additionally, operation of the tankless water heater is modified to ensure that the exhaust generated is suitable for venting through a Category I vent. The tankless water heater maintains a high fuel consumption rate such that the temperature of hot water produced increases throughout each of a plurality of burner stages.

The disclosed technology includes a controller for a cascade boiler system having both condensing and non-condensing boilers. The controller can receive supply water temperature data and return water temperature data to determine a current temperature differential in the system. The controller can determine a current load demand value using the current temperature differential and a set point temperature. If the current load demand value is less than or equal to a first load demand threshold, the controller can output a control signal for a condensing boiler to transition to a heating mode. If the current load demand value is greater than a second load demand threshold, the controller can output a control signal for a non-condensing boiler to transition to a heating mode.

A vent attachment facilitates attaching a coaxial air intake and exhaust vent of a tankless water heater to a Category I vent, such as B-vent. The vent attachment comprises a first end with a coaxial connector comprising a central exhaust pathway and a circumferential air intake pathway. The vent attachment also comprises a second end with a tubular exhaust vent connector in fluid communication with the central exhaust pathway. The vent attachment further comprises a frame that encloses the central exhaust pathway and comprises a mesh configured to provide fluid communication through the frame with the air intake pathway. Additionally, operation of the tankless water heater is modified to ensure that the exhaust generated is suitable for venting through a Category I vent. The tankless water heater maintains a high fuel consumption rate such that the temperature of hot water produced increases throughout each of a plurality of burner stages.

The disclosed technology includes systems and methods for controlling a water heater. The disclosed systems can be configured to receive temperature data from a temperature sensor, receive flow rate data from a flow rate sensor, and receive a temperature setting. The systems can calculate a heat load rate based on at least the temperature data, the flow rate data, and the temperature setting, and can compare the heat load rate to a predetermined threshold setting. The systems can output instructions to perform a fast corrective action in response to the determination that the heat load is changing at a rate (i.e. the heat load rate) greater than, less than, or equal to the predetermined threshold setting.

The disclosed technology includes a controller for a cascade boiler system having both condensing and non-condensing boilers. The controller can receive supply water temperature data and return water temperature data to determine a current temperature differential in the system. The controller can determine a current load demand value using the current temperature differential and a set point temperature. If the current load demand value is less than or equal to a first load demand threshold, the controller can output a control signal for a condensing boiler to transition to a heating mode. If the current load demand value is greater than a second load demand threshold, the controller can output a control signal for a non-condensing boiler to transition to a heating mode.

The disclosed technology includes systems and methods for controlling a water heater. The disclosed systems can be configured to receive temperature data from a temperature sensor, receive flow rate data from a flow rate sensor, and receive a temperature setting. The systems can calculate a heat load rate based on at least the temperature data, the flow rate data, and the temperature setting, and can compare the heat load rate to a predetermined threshold setting. The systems can output instructions to perform a fast corrective action in response to the determination that the heat load is changing at a rate (i.e. the heat load rate) greater than, less than, or equal to the predetermined threshold setting.

A vent attachment facilitates attaching a coaxial air intake and exhaust vent of a tankless water heater to a Category I vent, such as B-vent. The vent attachment comprises a first end with a coaxial connector comprising a central exhaust pathway and a circumferential air intake pathway. The vent attachment also comprises a second end with a tubular exhaust vent connector in fluid communication with the central exhaust pathway. The vent attachment further comprises a frame that encloses the central exhaust pathway and comprises a mesh configured to provide fluid communication through the frame with the air intake pathway. Additionally, operation of the tankless water heater is modified to ensure that the exhaust generated is suitable for venting through a Category I vent. The tankless water heater maintains a high fuel consumption rate such that the temperature of hot water produced increases throughout each of a plurality of burner stages.

A gas manifold allows each distribution chamber to be fed with fuel gas at an appropriate flow rate irrespective of an increase in the number of distribution chambers included in the gas manifold. A gas manifold distributes fuel gas flowing in through an inlet to a plurality of distribution chambers through a main channel. The main channel includes a flow guide that guides the fuel gas toward a maximum distribution chamber and reduces the fuel gas flowing into other distribution chambers. This allows fuel gas at a sufficient flow rate to be fed more easily to the maximum distribution chamber than to the other distribution chambers for a larger number of distribution chambers included in the gas manifold, allowing the plurality of distribution chambers to be fed with fuel gas at appropriate flow rates.

The water heater may be configured to execute a normal operation in which a heating means is continuously operated in an ON state in a case where a required heat quantity is greater than or equal to a minimum heat quantity. The water heater may be configured to execute an intermittent operation in which the heating means is alternately and repeatedly operated in the ON state and an OFF state repeatedly in a case where the required heat quantity is less than the minimum heat quantity. The water heater may be configured to change a distribution ratio of a flow control mechanism in the normal operation and in the intermittent operation. An operating speed of the flow control mechanism in the intermittent operation may be faster than an operating speed of the flow control mechanism in the normal operation.

A hot water supply device includes: a combustion part including a first burner part for which a flame sensor is disposed and a second burner part having a different number of burners from the first burner part such that one or both of the burner parts perform combustion, the flame sensor being configured to detect combustion state information of a flame generated by burners; a combustion control part configured to monitor a combustion mode of the combustion part set in accordance with a hot water supply request and change a second combustion mode in which the first burner part does not perform combustion, to a first combustion mode in which at least the first burner part performs combustion, when the second combustion mode is continuing; and a combustion adjustment control part configured to execute a combustion adjustment process of the combustion part.