System and methods for controlling operating state of a heat transfer system are disclosed herein. The heat transfer system can include temperature sensor positioned at the fluid inlet line and the fluid outlet line and a heat exchanger between the fluid inlet line and the fluid outlet line. The heat transfer system can include a processor communicatively coupled to the first temperature sensor and the second temperature sensor. The processor can determine an inlet temperature of water flowing in the fluid inlet line and outlet temperature of water flowing in the fluid outlet line and can determine a delta temperature based on difference between the inlet temperature and the outlet temperature. Based on the inlet temperature and the delta temperature, the processor can determine an operating state of the heat transfer system.

An on-demand hot water dispenser includes a housing, a water heating system received in the housing, and a faucet connected to the water heating system through the housing for dispensing hot water into a container. A drip tray is positioned below the faucet and a screen covers the drip tray to support the container during dispensing of the hot water.

The present invention becomes possible to employ a main microprocessor with a relatively lower number of input ports, whereby while maintaining the performance and function of a water heater, the cost of a control apparatus is cut down. Some of sensors, adapted for measurement of various parameters which are for use in operational control of the water heater and in need of immediate response, are connected to a main microprocessor 31. The other sensors that are not in need of an immediate response, such as an ambient temperature sensor 36, are connected only to a sub microprocessor 32 if the main microprocessor 31 does not have any extra analog signal input port. The sub microprocessor converts an analog signal from the sensor 36 which is connected only to the sub microprocessor into digital data. And the sub microprocessor transmits the digital data to the main microprocessor through communication therewith.

Embodiments of the invention provide a pool heater including a housing, a first tankless heater, a second tankless heater, and a controller. The controller is configured to activate only the first tankless heater when a first condition is met, activate only the second tankless heater when a second condition is met, and activate the first and the second tankless heaters simultaneously when a third condition is met.

Provided is a hot water supply apparatus. Processing executed by the hot water supply apparatus includes the following. A hot water supply set temperature is read from a memory. A maximum temperature of a housing is set by combustion level (combustion stage number) in accordance with a setting pattern predetermined according to the hot water supply set temperature. When it is intended to detect an end of operation of the hot water supply apparatus in the case of detecting no change in the hot water supply set temperature, a combustion operation is continued. The maximum temperature of the housing is set again by combustion level (combustion stage number) in the case of detecting a change in the hot water supply set temperature.

Provided is a hot water supply apparatus. Processing executed by the hot water supply apparatus includes the following. A hot water supply set temperature is read from a memory. A maximum temperature of a housing is set by combustion level (combustion stage number) in accordance with a setting pattern predetermined according to the hot water supply set temperature. When it is intended to detect an end of operation of the hot water supply apparatus in the case of detecting no change in the hot water supply set temperature, a combustion operation is continued. The maximum temperature of the housing is set again by combustion level (combustion stage number) in the case of detecting a change in the hot water supply set temperature.

A demand based control for a hydronic heating system varies the heat response based on an actual demand of the conditioned space, rather than an estimated thermal loss. Differences between supply and return of a heat transfer medium, such as forced hot water, are measured for the conditioned space, as well as the flow rate of the forced water to determine an actual thermal transfer to the conditioned space. A required heat generation is computed based on the measured transfer and resultant temperature change of the conditioned space, and heat generation parameters such as boiler firing rate and circulator pump speed varied to control the heat transfer to the conditioned space and avoid overshoot or excessive heat generation beyond that needed for the measured demand.

The autonomous energy saving device (2) enabling the control of a water heater (1) connected to a power grid comprising a phase P, a neutral N and a protective conductor T operating on a permanent power supply or during rate periods using a switch or timer, said energy saving device (2) comprises inputs E1, E2, E3 and the outputs S1, S2, S3 and between inputs E1 and E2 and the outputs S1 and S2 at least one primary circuit board (7) comprising at least one electronic component (3, 4) and a control algorithm to remove or reduce the heating times of the water heater (1) without changing the technical characteristics of the water heater, and in order to adapt its operation to the needs of the user.

A hot water circulation system comprises a water heater having a cold-water inlet and a hot water outlet. A water pump circulates water through the water heater to produce hot water. The hot water is circulated to a thermal bypass valve, which is configured to close when hot water contacts a heat activated seal. A bypass circuit is coupled between the hot water outlet and the cold water inlet of the water heater. The bypass circuit prevents hot water from circulating from the hot water outlet to the cold-water inlet when the thermal bypass valve is open and promotes circulating hot water from the hot water outlet to the cold water inlet when the thermal bypass valve is closed. Upon a temperature sensor sensing hot water entering the cold-water inlet, the water heater turns of the water pump.

A hose nozzle assembly which is capable of heating water comprising an internal heating chamber with at least one heating element. The hose nozzle assembly is able to heat water from a common garden hose with the ability to control both flow rates and temperature.