A heat exchanger assembly, comprising: heat exchanger pipework which comprises a plurality of elongate tube elements which extend in spaced relation and a plurality of pipe end couplings which fluidly connect open ends of respective tube elements, wherein the pipe end couplings each comprise a main body part to which the open ends of the respective tube elements are fixed, and an enclosure part which is fixed to the main body part and provides a closed fluid connection between the open ends of the respective tube elements; and a plurality of fins which extend in spaced relation and optionally substantially orthogonally to the tube elements, wherein the fins each comprise a sheet element, optionally a single, continuous sheet element, which includes a plurality of apertures through which extend respective ones of the tube elements, and a plurality of fin coupling elements which are located within respective ones of the fin apertures to interface the tube elements to the sheet elements.