Abstract: In a chemical heat pump a substance is used which within the temperature range for which the heat pump is intended has a transition between a solid phase and a solution phase. The substance can for a solar driven chemical heat pump comprise magnesium chloride hexahdrate. In an accumulator part of the heat pump a heat exchanger (21) is provided enclosed by a net (23). The solid phase is primary located inside the net in contact with the heat exchanger while the solution phase flow out of the net and is collected in space (24′) below the heat exchanger. From this space the solution phase is pumped and sprayed over the heat exchanger from a spray bar (25). Thereby, all the time equilibrium is maintained. The advantage including the constant temperature step and the relatively large energy content of solid substance is thereby combined with the high power of liquid substances.