Provided is an RPM control method for an inducer for a gas furnace that induces a flow of combustion gas produced in a burner from a heat exchanger to an exhaust pipe. The RPM control method for an inducer for a gas furnace includes: (a) initiating a heating operation for the gas furnace; (b) determining whether the operation time during which the heating operation is performed is equal to or longer than a first time period; (c) if it is determined that the operation time is equal to or longer than the first time period, detecting whether a pressure switch is turned OFF; and (d) if the pressure switch is detected as turned OFF, increasing the RPM of the inducer by a first value.

A freeze protection system is provided that includes a first valve configured to be coupled with an inlet of a water heater, such as a tankless water heater; a second valve configured to be coupled with an outlet of the water heater; and a valve actuator configured to automatically actuate the first valve and the second valve to permit water to drain from the water heater when (1) electric power is lost to the water heater, and (2) a temperature of a fluid in or around the water heater is less than or equal to a predetermined low temperature threshold.

A combination water heating, air conditioning refrigerant system is described. The combined system includes a plurality of independently adjustable electronic expansion valves. The expansion valves can independently modulate the delivery of high-temperature, high-pressure refrigerant to either a water heat exchanger or an outside condenser. A controller can receive input signals, including temperature signals from one or more temperature sensors that indicate the temperature at various locations of the system. The temperature signals include one or more of water temperature signals, ambient air temperature signals, or refrigerant super heat temperatures signals. In response to the input signals, the controller can output control signals to one or more of the plurality of electronic expansion valves.

A composite refrigeration system includes a refrigeration part, a heat dissipation part, a first pipeline, a second pipeline, and a refrigerant. The refrigeration part uses the refrigerant to cool air sent into indoor space, and the heat dissipation part is configured to perform heat dissipation on the refrigerant. In addition, in two heat dissipation modes, the heat exchanger may exchange heat between the refrigerant and a heat carrier in an external pipeline network to implement heat dissipation. The composite refrigeration system implements, by using the heat exchanger, a function of exchanging heat with the external pipeline network, so that heat generated during operation of the composite refrigeration system can be at least partially transferred to the heat carrier in the external pipeline network, to implement the energy recycle and reuse.

A fluid sensor system detects one or more performance characteristics of a heating system that heats a fluid. The sensor system includes a probe having a finite length a portion of which is to be immersed in the fluid. The probe includes a resistive heating element and a fluid temperature sensor for measuring one or more performance characteristics, wherein the fluid temperature sensor is configured to measure a fluid temperature, and the resistive heating element is operable as a heater to create a temperature differential between the fluid and air to detect the fluid, and as a sensor to measure a fluid level.

An indicator generating method for generating an indicator which is suitable for maintenance prediction of a water heating system is proposed. A power state indication device generates a high power consumption signal if a heating device of the water heating system is activated. The time duration of the activation is such an indicator, if no water flow is present. Furthermore, the time interval between subsequent activations is such an indicator. A predictive maintenance method processes these condition-based indicators and determines a remaining useful lifetime according to a predictive maintenance model. The predictive maintenance device outputs a maintenance signal indicating required maintenance, if the remaining useful lifetime drops below a predetermined threshold. The methods may be performed by water heating systems or beverage makers.

This invention relates to a heater. A combustion air blower feeds combustion air to a burner device. The burner device burns a gas-air mixture from the combustion air and a fuel and serves for heating air. A circulating air blower discharges heated air from the heater. A control device acts on at least one component of the heater, wherein a night mode parameter set associated with an operation of the heater in a night mode and a default parameter set are stored in a data storage device. After an activation of the night mode, the control device accesses the night mode parameter set and uses the same for acting on the component. The night mode parameter set effects a reduction of background noise generated by the heater.

The flameless heater system includes an energy source comprising a diesel engine configured to create volumes of air, a hydraulic system to control engine loading for heat generation and for air moving, and a control system, operatively coupled with the energy source and the hydraulic system to control at least one of a speed of the diesel engine, a loading of the diesel engine, or a fan speed.

Provided is a gas furnace including a primary heat exchanger and a secondary heat exchanger through which a combustion gas produced by the combustion of a fuel gas flows. The gas furnace includes: a coupling box serving as an intermediary to connect the primary heat exchanger and the secondary heat exchanger; a collect box connected to the secondary heat exchanger, for letting in the combustion gas passed through the secondary heat exchanger; an inducer connected to the collect box, for inducing a flow of the combustion gas; and a bypass pipe connected to one side of the coupling box and including a bypass pipe for guiding the combustion gas passed through the primary heat exchanger to a hot water supply tank for supplying hot water to an indoor space.

A control system is provided for controlling heating and/or cooling with a conditioning load such as fan coils and chilled beams. Based on user input and ambient conditions, the control system determines a desired temperature for the liquid entering the load and combines fresh supply liquid (e.g., from a chiller or boiler) with a portion of the liquid that has passed through the load, to achieve the target load input temperature for the liquid. A recirculation pump may be used to return a portion of the liquid exiting the load for mixing with the fresh supply liquid and a control valve may be used to adjust the ratio of fresh supply liquid and recirculated liquid to achieve the targeted temperature. The control systems can be compatible with a variety of liquid supply systems such as two- and four-pipe systems.