This essay investigates which parameters that control the efficiency of an absorption heat pump. The investigation results in an optimization of best efficiency for the absorption process at different cooling media temperatures. An economic calculation of cost per produced unit of energy at varying investment cost for the absorption heat pump and heat storage tank was also carried out. The absorption heat pump will produce heat-energy for heating radiator water and tap warm water for a normal sized dwelling. The working fluid pair combination in the absorption heat pump consists of lithium bromide as transport media and water as cooling media. The heating system consists of a single stage absorption heat pump of type Absorption Heat Pump. The Absorption heat pump is supplied with high temperature driving force-energy from a pellet boiler and energy with low temperature from groundwater. A heat storage tank accumulates the produced energy from the absorption heat pump. The absorption heat pump supply the heat storage tank with heat energy by a coil containing circulating water, which is named cooling media coil, to bring heat energy from the absorption heat pump. The media in the cooling media coil, which is water, is warmed by the absorption heat pump to a temperature of 80?C with inlet temperatures from 7°C up to 30°C. Best efficiency for the absorption heat pump varies from 1,728 to 1,424 when the incoming cooling media temperatures vary from 7°C to 30°C. According to the economic calculations the investment, for absorption heat pump and heat storage tank, may rise to 111 000 SEK when incoming cooling media temperature is 7°C. The investment for absorption heat pump and heat storage tank may rise to 96 000 SEK when incoming cooling media temperature is 30°C.