A method for saving energy by shutting down unnecessary equipment in a water heating system and setting back temperature setpoints to reduce energy losses. The present method is aimed at reducing energy wastage due to unnecessary external recirculation and overly high temperature setpoint for the external recirculation flow when no demands exist for an extended period of time.

A heating apparatus includes two heating circuits (3, 4), one for room heating (3) and one for domestic water heating (4). A primary heat exchanger (1) is provided as well as at least one secondary heat exchanger (7), for the room heating as well as a secondary heat exchanger (9) for domestic water heating. A circulation pump (6) is provided as well as a switch-over valve (5) which hydraulically integrates the primary heat exchanger (1) into the first or into the second heating circuit (3, 4). The heating circuit (4) for the domestic water heating, on operation of the heating circuit (3) for room heating, is used as a bypass conduit for the primary heat exchanger (1), wherein the switch-over valve (5) forms the bypass valve or is used as a bypass valve.

A combined space conditioning or heating and fluid heating system includes a main fluid conductor having an inlet and an outlet; a single heating source configured for producing low and high temperature fluid outputs of a fluid input received at the main fluid conductor inlet; a coil comprising an inlet and an outlet; and a supplementary fluid conductor comprising a fluid mover and a directional valve, an inlet and an outlet. The inlet of the main fluid conductor is adapted for connection with the coil outlet. The high temperature fluid output is adapted for connection with the supplementary fluid conductor inlet, the supplementary fluid conductor outlet is adapted for connection with the coil inlet. The low temperature water output is adapted for connection with a fluid delivery point. The water coil inlet is adapted for connection with a raw fluid supply.

A heating device with hot water supply function includes: a combustion means; a main heat exchanger; a circulation passage connecting the main heat exchanger to an heating apparatus; a circulation pump provided in the circulation passage; a bypass passage that branches off from the circulation passage and bypasses the room heating apparatus; a secondary heat exchanger provided in the bypass passage; a cold water supply passage for supplying cold water to the secondary heat exchanger; a hot water supply passage for supplying hot water heated by the secondary heat exchanger; a hot water supply bypass passage that connects the cold water supply passage to the hot water supply passage bypassing the secondary heat exchanger; a flow adjustment means for adjusting the flow rate in the hot water supply bypass passage and thereby controlling the temperature of hot water to be supplied; and an expanded passage portion of the hot water supply passage whose diameter is increased from an intermediate portion of the hot water supply passage to its downstream end.

A weather forecast-based fluid heating control system having at least one hot fluid delivery point, the control system including a controller adapted to control a fluid supply to a setpoint temperature, a means for obtaining the forecasted air temperature at a future time of the location of the control system and a means for obtaining the current air temperature at a current time of the location of the control system. The setpoint temperature of the fluid supply is adjusted by an adjustment amount if the difference between the forecasted air temperature of the location of the control system and the current temperature at the current time of the location of the control system exceeds a pre-determined threshold.

A hot water-centered hot water and heating combination boiler includes: a cold water inflow tube through which cold water flows in; a main heat exchanger which heats the cold water flowing in through the cold water inflow tube by using the combustion heat of a burner; a hot water discharge tube which discharges the hot water heated in the main heat exchanger; an auxiliary heat exchanger which supplies heating water during a heating mode, in which heating consumption place, and causes heat exchange to occur between the heated water in the main heat exchanger and the lowered temperature returning water, in which the heating consumption place; and a control part which controls the combustion of the burner during a hot water mode and heating mode.

A combination boiler provides heated water to a boiler loop and heated domestic hot water (DHW) to a DHW loop. A primary heat exchanger is connected to the boiler loop. A burner provides heat to the primary heat exchanger and an input fan supplies a fuel and air mixture to the burner. A secondary heat exchanger transfers heat energy from the boiler loop to a domestic water loop. A controller determines a boiler loop flow rate. The controller measures an input temperature of the boiler loop, an output temperature of the boiler loop, and a DHW output temperature of the domestic water loop. The controller determines a DHW input temperature and estimates a DHW flow rate. The input fan speed is initiated or operated according to a required heat output of the burner corresponding to the DHW flow rate.

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.

A water heating apparatus, including: a heat source circuit including a first circulation pump, a heat pump, and a heat source side of a hot water supply tank heat exchanger that are connected to each other by a pipe, the heat source circuit being configured to allow water to circulate therethrough; a hot water supply circuit including a second circulation pump, a use side of the hot water supply tank-use heat exchanger, and a hot water supply tank that are connected to each other by a pipe, the hot water supply circuit being configured to allow water to circulate therethrough; and a control unit configured to perform, when the hot water supply tank temperature falls below the reheating tank temperature, reheating, and control a flow rate of the second circulation pump.

A multi-temperature output fluid heating system including an input for receiving a fluid supply, a single heating source, a first output, a second output and a bypass path. The first output is fluidly connected to the input, where the first output is adapted for control by a first control device and to receive heat from the single heating source to achieve a first temperature at the first output. The bypass path fluidly connects the input and the second output. The input is adapted to empty a first portion of the fluid supply into the first output and a second portion of the input into the bypass path. The second output is adapted to receive an output from the first output and an output from the bypass path to achieve a second temperature.