A retrofit heat pump system for a water heater is disclosed. The heat pump system includes a plurality of evaporators to increase the efficiency of heat exchange for the system. The system can also include a plurality of condenser circuits used to heat the water of an existing water tank. A fan disposed in a housing of the heat pump system can draw air across the plurality of evaporators and exhaust cool air external to the heat pump system. The cool air can be exhausted into duct work associated with an air conditioning system of the home. The disclosure also describes a refrigerant distributor for providing uniform liquid refrigerant to the plurality of evaporators.

In a method for operating a heating device, fluid is initially introduced into a fluid chamber, then the heating elements of the heating device are switched on and a leakage current is detected as a temperature-dependent current flow through a dielectric insulation layer. A supply voltage of the heating devices is measured and is taken into account in an evaluation of the temperature at the fluid chamber as a function of the leakage current. The leakage current is converted into a leakage voltage by means of a resistor, which is then divided by the measured supply voltage. Subsequently, the quotient obtained may be multiplied by a compensation value in order to obtain a normalized leakage signal, which is normalized to a base value of the supply voltage. The normalized leakage signal is used, if a particular absolute value of the leakage signal is exceeded or if a particular slope of the profile of the leakage signal is exceeded, in order to top up the fluid chamber with more fluid and/or to reduce the heating power of at least one heating element.

A heat trap apparatus for a water heater is provided. The heat trap apparatus includes a tubular body, a liner disposed within the tubular body, and a heat trap baffle assembly having a tubular housing coaxially disposed within the liner. The liner includes a projection to engage with an inner surface of the tubular body at a first end using an interference fit. The tubular housing includes a first diametric portion to engage with the inner surface of the tubular body at a second end using an interference fit, a second diametric portion extending from the first diametric portion and to engage with an inner surface of the liner using an interference fit, and a third diametric portion extending from the second diametric portion and to movably support one or more heat trap inserts to inhibit convective fluid flow therethrough.

A heat trap apparatus for a water heater is provided. The heat trap apparatus includes a tubular body having a length defined between a first end and a second end, a liner disposed within the tubular body, and a heat trap baffle assembly having a tubular housing coaxially disposed within the liner to inhibit convective fluid flow therethrough. The liner has a length greater than the length of the tubular body and has an outer surface engages with an inner surface of the tubular body using an interference fit. The liner includes a first end engaging with a peripheral edge of the first end of the tubular body and a second end extending beyond a peripheral edge of the second end of the tubular body for a desired length to connect with a conduit.

An improved boiler apparatus having multiple resistive heating elements are provided with fixed resistances that can be rewired to allow dual voltage capability and at the same time, reduced watt density. For 120V operation, the large diameter 9-ohm coil is used alone to provide the lowest possible watt density. For 240V operation, all three heating coils are wired in series, creating a low watt density but high wattage heater.

An electrical power distribution control system configured to issue a demand response signal to cut power to a plurality of electrical power consuming loads within an electrical power distribution network to reduce a peak power demand within an electrical power grid during a peak power demand. Unlike conventional demand response systems, the controller in each consumer residence includes both a distributed control based on the ability to track individual 24 hour usage patterns and selectively delay the demand response signal on individual resistive heating loads based on usage patterns for the purpose of reducing a likelihood of consumers experiencing effects of the reduced peak power demand.

Systems and methods for a thermosyphonic water heating system for a storage tank. A DC heat pump receives power from a DC power source and heats water via a heat exchanger using a thermosyphonic piping system. A passive back-flushing having a cold water inlet pipe connected to the hot water return pipe draws cold water into the storage tank through the heat exchanger. A vertical array of temperature sensors distributed throughout the storage tank monitor temperature of stored water at multiple heights and a communication unit communicates monitored data to an external control device.

Control of temperature of water delivered by a dual-stage water heater having an external boiler with a first heater as first stage and an internal duct (water booster) with a second heater as second stage. A control loop based on a measured water temperature in the boiler and controls the first heater. A second loop calculate a reference booster water temperature based on the temperature error at the outlet (difference between a measured outlet water temperature and a reference outlet water temperature) and controls second heater based on error between reference booster water temperature and measured booster water temperature. The reference outlet water temperature depends on type of beverage (e.g. espresso, cappuccino) and includes a temperature profile with different temperature for different sub-beverages (e.g. coffee, milk). Takes into account physical response times, inertia of heater and anticipate sudden changes of reference water temperature at hot water outlet.

Tank (1) comprising a chamber (2) to receive liquid, a shell (3) surrounding the chamber (2) and a resistive electric element (13) that can be positioned inside the chamber (2). The tank comprises two orifices (5, 6) facing each other, one of them (5) formed in the chamber (2) and the other (6) in the shell (3) and connected by a casing body (7) comprising a bottom (8) and a peripheral side wall (9), the casing body (7) and the chamber are made of a synthetic material, the casing body (7), of which the bottom (8) is holed, forms a connecting sleeve connecting said orifices (5, 6) to one another, the hole in the bottom (8) is externally bordered by a rim to form a tubular projection (12) inserted into the orifice (5) of the chamber (2), and the resistive electric element (13) takes the form of an elongate body fitted with a seal configured so that, in collaboration with the resistive electric element (3), it seals the hole.

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.