A heating and cooling system comprises: a heating system having a demand for heated water; and a refrigeration system comprising pipework enabling flow of refrigerant, an evaporator within a chilled space, a compressor, a condenser which is located in a space separate from the chilled space, a first expansion device, switching means (56; 64, 66) configured to control a flow path of refrigerant in dependence on whether there is cooling demand with or without heating demand, or only heating demand; a first plate heat exchanger in which heat is exchanged between the refrigerant flowing from the compressor through a first side of said first plate heat exchanger whilst the heating system water flows through a second side of said first plate heat exchanger; a second plate heat exchanger having a first side connected to the refrigerant output of the first plate heat exchanger; and a second expansion device; wherein the switching means (56; 64, 66) is configured such that, when there is cooling demand with or without heating demand, the switching means (64, 66) causes the refrigerant leaving the first side of the first plate heat exchanger to flow through a first side of the second plate heat exchanger directly to the condenser; wherein the switching means (56; 64, 66) is further configured such that, when there is only heating demand, the switching means (64,66) causes the refrigerant to take a flow path leaving the first side of the first plate heat exchanger to flow to a first side of the second plate heat exchanger to the condenser to the second expansion device to a second side of the second plate heat exchanger before it goes directly back to the compressor a heating system having a demand for heated water; and a refrigeration system comprising pipework enabling flow of refrigerant, an evaporator within a chilled space, a compressor, a condenser which is located in a space separate from the chilled space, a first expansion device, switching means (56; 64, 66) configured to control a flow path of refrigerant in dependence on whether there is cooling demand with or without heating demand, or only heating demand; a first plate heat exchanger in which heat is exchanged between the refrigerant flowing from the compressor through a first side of said first plate heat exchanger whilst the heating system water flows through a second side of said first plate heat exchanger; a second plate heat exchanger having a first side connected to the refrigerant output of the first plate heat exchanger; and a second expansion device; wherein the switching means (56; 64, 66) is configured such that, when there is cooling demand with or without heating demand, the switching means (64, 66) causes the refrigerant leaving the first side of the first plate heat exchanger to flow through a first side of the second plate heat exchanger directly to the condenser; wherein the switching means (56; 64, 66) is further configured such that, when there is only heating demand, the switching means (64,66) causes the refrigerant to take a flow path leaving the first side of the first plate heat exchanger to flow to a first side of the second plate heat exchanger to the condenser to the second expansion device to a second side of the second plate heat exchanger before it goes directly back to the compressor pipework enabling flow of refrigerant, an evaporator within a chilled space, a compressor, a condenser which is located in a space separate from the chilled space, a first expansion device, switching means (56; 64, 66) configured to control a flow path of refrigerant in dependence on whether there is cooling demand with or without heating demand, or only heating demand; a first plate heat exchanger in which heat is exchanged between the refrigerant flowing from the compressor through a first side of said first plate heat exchanger whilst the heating system water flows through a second side of said first plate heat exchanger; a second plate heat exchanger having a first side connected to the refrigerant output of the first plate heat exchanger; and a second expansion device; wherein the switching means (56; 64, 66) is configured such that, when there is cooling demand with or without heating demand, the switching means (64, 66) causes the refrigerant leaving the first side of the first plate heat exchanger to flow through a first side of the second plate heat exchanger directly to the condenser; wherein the switching means (56; 64, 66) is further configured such that, when there is only heating demand, the switching means (64,66) causes the refrigerant to take a flow path leaving the first side of the first plate heat exchanger to flow to a first side of the second plate heat exchanger to the condenser to the second expansion device to a second side of the second plate heat exchanger before it goes directly back to the compressor