A hot-water supply device includes a hot-water dispenser supplying hot-water, a hot-water supply path supplying the hot-water to a hot-water supply tap, a circulation path carrying out instant hot-water operation which circulates and heats the hot-water remaining in the hot-water supply path, a first clock repeatedly measuring unit times in which a pattern of hot-water usage of a user makes a round, and a flow rate sensor detecting the supply of the hot-water from the hot-water supply tap. The control portion detects, for each of the unit times and based on detection signals of the flow rate sensor, a time zone in which hot-water supply operation is carried out, and reserves, based on a time zone in a first unit time in which the hot-water supply operation is carried out, a time zone in a second unit time following the first unit time for carrying out the instant hot-water operation.

A water heating system can include a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on a plurality of algorithms and measurements made by the first and second temperature sensors. The plurality of algorithms solves for at least one calculated temperature for at least one point between a first location of the first temperature sensor and a second location of the second temperature sensor, where the at least one calculated temperature is used to determine the amount of heated water in the tank.

As a circulation pump is activated while a hot water supply faucet is closed, an immediate hot water supply circulation path is formed to bypass the hot water supply faucet on the outside of a water heating apparatus and to pass through a heat exchanger in the inside of the water heating apparatus. A controller determines in a test mode, whether or not the immediate hot water supply circulation path has been formed by connection of a thermal water stop bypass valve, based on whether or not a temperature detector senses increase in temperature to a predetermined criterion temperature while the circulation pump and a heat source apparatus are active.

A scale adhesion prevention operation of a circulation pump operated in an instant hot water operation is efficiently and appropriately performed. An instant hot water circulation path is formed to bypass a hot water tap outside a hot water supply device and to pass through a heat exchanger inside the hot water supply device by operating a circulation pump when the hot water tap is closed. A controller performs a protection operation which operates the circulation pump when a first condition in which stop of the circulation pump is continued for a first time is satisfied and a second condition related to stop of a hot water supply operation is further satisfied.

A heating, ventilation, and air conditioning system in which a primary water loop is used as a heat transfer reservoir for both heating and cooling. A plurality of micro chillers are provided, with each micro chiller being connected to the primary water loop. Each micro chiller includes its own heat engine. Each micro chiller includes one or more fan control units that exchange heat between the micro chiller and the air in a building. In a first mode a micro chiller transfers heat from the air in the building to the water circulating within the primary water loop. In a second mode the micro chiller transfers heat from the water circulating in the primary water loop to the air in the building. A primary water loop regulation system is provided to control the temperature of the water circulating in the primary water loop.

A water heater system includes a controller configured to integrate control of both recovery and recirculation operations of a recovery pump and a recirculation pump. As such, a separate device, installation location, and power source (e.g., available outlet) is not needed with the controller. Because a single controller is configured to control both recovery and recirculation operations, additional control functions are available. The controller may be in communication with an internal controller of the water heater and configured to receive an error notification upon abnormal operation of the water heater. The controller can stop recovery and recirculation operations in response to an error notification, unlike with traditional water heating systems which may otherwise continue to function. The recovery and recirculation operations are based on a setpoint temperature of the water heater such that changes made to the setpoint temperature will automatically adjust in the recovery and recirculation operations.

A water heater system includes a controller configured to integrate control of both recovery and recirculation operations of a recovery pump and a recirculation pump. As such, a separate device, installation location, and power source (e.g., available outlet) is not needed with the controller. Because a single controller is configured to control both recovery and recirculation operations, additional control functions are available. The controller may be in communication with an internal controller of the water heater and configured to receive an error notification upon abnormal operation of the water heater. The controller can stop recovery and recirculation operations in response to an error notification, unlike with traditional water heating systems which may otherwise continue to function. The recovery and recirculation operations are based on a setpoint temperature of the water heater such that changes made to the setpoint temperature will automatically adjust in the recovery and recirculation operations.

Appropriate ventilation for a building space while maintaining building comfort includes tracking one or more interior environmental conditions within the building space and one or more exterior environmental conditions outside of the building space during operation of the HVAC system. An environmental model for the building space is learned over time based at least in part on these tracked environmental conditions, where the environmental model predicts an environmental response of the building space to operation of the HVAC system under various interior and exterior environmental conditions. An appropriate ventilation rate that maintains adherence to one or more comfort parameters of the building space is determined by using the environmental model of the building space. The outdoor air ventilation damper of the HVAC system is controlled to provide appropriate ventilation.

A combination space and water heating apparatus includes a frame enclosing a water heating assembly and an air heating assembly. The water heating assembly is positioned in a top front portion of the frame and supplies hot water in response to a hot water demand. The water heating assembly includes inlet and outlet water connections through a top portion of the water heating assembly. The air heating assembly is positioned in a rear and bottom portion of the frame and supplies heated air in response to a space heating demand. Maintenance access to the air heating assembly is solely through a front section of the bottom portion of the frame.

A combination space and water heating apparatus includes a frame enclosing a water heating assembly and an air heating assembly. The water heating assembly is positioned in a top front portion of the frame and supplies hot water in response to a hot water demand. The water heating assembly includes inlet and outlet water connections through a top portion of the water heating assembly. The air heating assembly is positioned in a rear and bottom portion of the frame and supplies heated air in response to a space heating demand. Maintenance access to the air heating assembly is solely through a front section of the bottom portion of the frame.