A combination boiler provides heated water to a boiler loop and domestic hot water (DHW) to a domestic water loop. The combination boiler includes a primary heat exchanger (PHE) connected to the boiler loop and a burner to provide heat to the primary heat exchanger. A secondary heat exchanger (SHE) transfers heat energy from the boiler loop to the domestic water loop. A controller monitors a PHE inlet temperature and a DHW output temperature, obtains a pre-heat initialization temperature threshold and a pre-heat cancellation temperature threshold, and detects a low temperature condition. A pre-heat operation is initiated responsive to the low temperature condition by circulating heated water from the PHE to the SHE. The burner is selectively fired at least in part according to an outlet temperature of the PHE.

The present invention provides a combined heating and hot-water boiler for heating and hot-water. The combined heating and hot-water boiler comprises: a main heat exchanger which heats heating water through heat exchange; a hot-water heat exchanger to which the heating water heated by the main heat exchanger is supplied, and which heats tap water into hot water through heat exchange with the heating water; and a control unit which controls the flow of the heating water having passed through the hot-water heat exchanger to control the formation of at least one of a first flow path for supplying, to an object to be heated, the heating water having passed through the hot-water heat exchanger, and a second flow path for supplying, to the main heat exchanger, the heating water having passed through the hot-water heat exchanger.

The present invention provides a combined heating and hot-water boiler for heating and hot-water. The combined heating and hot-water boiler comprises: a main heat exchanger which heats heating water through heat exchange; a hot-water heat exchanger to which the heating water heated by the main heat exchanger is supplied, and which heats tap water into hot water through heat exchange with the heating water; and a control unit which controls the flow of the heating water having passed through the hot-water heat exchanger to control the formation of at least one of a first flow path for supplying, to an object to be heated, the heating water having passed through the hot-water heat exchanger, and a second flow path for supplying, to the main heat exchanger, the heating water having passed through the hot-water heat exchanger.

The invention is a double-circuit electric boiler for boiling a warming heat-carrying agent and a residential hot water. A hot water supply circuit first container and a second container with an electric heater for the heat-carrying agent of a warming circuit are arranged in a housing. Outer surfaces of inner walls of the warming circuit second container are in a contact with the water of the hot water supply circuit inside the first container. The electric heater for the heat-carrying agent is isolated by the second container walls from a contact with the water of the hot water supply circuit inside the first container. Both containers have separate inlet and outlet ducts and separate isolated temperature sensors. In a second embodiment of the boiler, an electric heater having heating areas isolated by the inner walls of the second container is further mounted in the first container.

The invention is a double-circuit electric boiler for boiling a warming heat-carrying agent and a residential hot water. A hot water supply circuit first container and a second container with an electric heater for the heat-carrying agent of a warming circuit are arranged in a housing. Outer surfaces of inner walls of the warming circuit second container are in a contact with the water of the hot water supply circuit inside the first container. The electric heater for the heat-carrying agent is isolated by the second container walls from a contact with the water of the hot water supply circuit inside the first container. Both containers have separate inlet and outlet ducts and separate isolated temperature sensors. In a second embodiment of the boiler, an electric heater having heating areas isolated by the inner walls of the second container is further mounted in the first container.

When a voltage signal is input to input terminals as a positive voltage, the voltage conversion circuit generates a control voltage proportional to an input voltage by a voltage-dividing circuit according to resistance elements, a voltage follower circuit according to an operational amplifier, and a voltage-dividing circuit according to resistance elements. When a voltage signal is input to the input terminals as a negative voltage, since the operational amplifier outputs a power supply voltage according to an input of the negative voltage, the voltage conversion circuit generates a predetermined positive voltage obtained by dividing the power supply voltage by the resistance elements as the control voltage. The predetermined positive voltage is higher than a voltage range of the control voltage when the voltage signal is input as the positive voltage.

When a voltage signal is input to input terminals as a positive voltage, the voltage conversion circuit generates a control voltage proportional to an input voltage by a voltage-dividing circuit according to resistance elements, a voltage follower circuit according to an operational amplifier, and a voltage-dividing circuit according to resistance elements. When a voltage signal is input to the input terminals as a negative voltage, since the operational amplifier outputs a power supply voltage according to an input of the negative voltage, the voltage conversion circuit generates a predetermined positive voltage obtained by dividing the power supply voltage by the resistance elements as the control voltage. The predetermined positive voltage is higher than a voltage range of the control voltage when the voltage signal is input as the positive voltage.

Provided is a heating and hot water supply device. The heating and hot water supply device includes: a combustion part; a heat exchanger; a circulation passage; a circulation part; a bypass passage; a distribution means for distributing the heating medium to the circulation passage and the bypass passage; a hot water supply heat exchanger; a water supply passage; and a hot water supply passage (21). The distribution ratio of the distribution means is adjustable so as to correspond to a heating operation, a hot water supply operation, and the simultaneous heating and hot water supply operation. The heating and hot water supply device includes an operation part, which heats the heating medium to one or more heating terminal setting temperatures and circulates the heating medium, and switches a setting of the one or more heating terminal setting temperatures to be increased by a prescribed temperature during the simultaneous heating and hot water supply operation.

Provided is a heating and hot water supply device. The heating and hot water supply device includes: a combustion part; a heat exchanger; a circulation passage; a circulation part; a bypass passage; a distribution means for distributing the heating medium to the circulation passage and the bypass passage; a hot water supply heat exchanger; a water supply passage; and a hot water supply passage (21). The distribution ratio of the distribution means is adjustable so as to correspond to a heating operation, a hot water supply operation, and the simultaneous heating and hot water supply operation. The heating and hot water supply device includes an operation part, which heats the heating medium to one or more heating terminal setting temperatures and circulates the heating medium, and switches a setting of the one or more heating terminal setting temperatures to be increased by a prescribed temperature during the simultaneous heating and hot water supply operation.

A system and method for enhanced hydrocarbon recovery utilizing steam. The system may include a high pressure water pump supplying pressurized water to a heat exchanger within a combustion heater to form supercritical steam that is provided to a reservoir. The combustion heater may be a surface mounted heater or a downhole steam generator.