A washing apparatus comprising: a casing having a top cover, a chamber for receiving goods to be washed, a heat pump comprising a first heat exchanger, a second heat exchanger, a compressor and a pressure lowering device forming a circuit comprising a refrigerant, the first heat exchanger being adapted to cool said refrigerant and to heat washing water to be used in the chamber, the second heat exchanger being adapted to heat said refrigerant and to cool an auxiliary fluid, and a thermal storage tank adapted to contain a liquid, wherein said second heat exchanger comprises at least one heat exchanger module, said module including: an inlet header to direct a flow of said refrigerant into said module; an outlet header to discharge a flow of said refrigerant from said module; and a plurality of heat exchange layers fluidly connecting said inlet to said outlet header to enable said refrigerant to flow from said inlet to said outlet header and/or vice versa; said layers being stacked one above the other in a predetermined direction, each heat exchange layer including a plurality of channels; wherein said second heat exchanger is adapted to heat said refrigerant and to cool the liquid contained in the thermal storage tank, said auxiliary fluid being said liquid contained in said thermal storage tank; and a worktop, said worktop including the top cover and a hollow cavity forming said thermal storage tank. a casing having a top cover, a chamber for receiving goods to be washed, a heat pump comprising a first heat exchanger, a second heat exchanger, a compressor and a pressure lowering device forming a circuit comprising a refrigerant, the first heat exchanger being adapted to cool said refrigerant and to heat washing water to be used in the chamber, the second heat exchanger being adapted to heat said refrigerant and to cool an auxiliary fluid, and a thermal storage tank adapted to contain a liquid, wherein said second heat exchanger comprises at least one heat exchanger module, said module including: an inlet header to direct a flow of said refrigerant into said module; an outlet header to discharge a flow of said refrigerant from said module; and a plurality of heat exchange layers fluidly connecting said inlet to said outlet header to enable said refrigerant to flow from said inlet to said outlet header and/or vice versa; said layers being stacked one above the other in a predetermined direction, each heat exchange layer including a plurality of channels; an inlet header to direct a flow of said refrigerant into said module; an outlet header to discharge a flow of said refrigerant from said module; and a plurality of heat exchange layers fluidly connecting said inlet to said outlet header to enable said refrigerant to flow from said inlet to said outlet header and/or vice versa; said layers being stacked one above the other in a predetermined direction, each heat exchange layer including a plurality of channels; wherein said second heat exchanger is adapted to heat said refrigerant and to cool the liquid contained in the thermal storage tank, said auxiliary fluid being said liquid contained in said thermal storage tank; and a worktop, said worktop including the top cover and a hollow cavity forming said thermal storage tank.