At present magnetic refrigeration shows a realistic potential to penetrate into some niche markets in the field of cold and hot "production". It is well known that a refrigerator for cooling and a heat pump for heating are machines based on the same principle. A small review on magnetic heat pump studies is outlined and a simple engineering calculation scheme to determine the coefficient of performance for a magnetic heat pump with a rotary porous structure heat exchanger is presented. Magnetic heat flux line distributions are calculated by a 2-d finite element method numerical simulation program with the objective to obtain high field's mu H-0 with not too heavy permanent magnets assemblies. The porous structures are geometrically optimised to obtain maximal magnetic field inductions. It is shown that for a water/ethylene-glycol magnetic heat pump the coefficient of performance is higher than that of a conventional heat pump. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.