Das Projekt "Waermepumpen mit Absorber-Waermetauschern" wird vom Umweltbundesamt gefördert und von Energietechnik GmbH Studiengesellschaft für Energie-Umwandlung, -Fortleitung und -Anwendung durchgeführt. Objective: The demonstration of novel absorber type heat exchanger using environmental heat in combination with electric heat pumps for room heating purposes. General Information: One 8 dwellings multifamily building is equipped with an energy stack of 220 m2 absorber surface and a brine-water heat pump with a capacity of 48.5 kwth. Also one single family house is equipped with an energy fence of 43,2 m2. absorber surface and a brine water heat pump with a capacity of 11 KW/th. The heat pumps are of the bivalent type. When outside air temperatures are below 3 C the existing oil fired boilers are used. The energy stack is installed on the roof of the building and consists of 40 horizontally arranged heat exchanger plates of anodised aluminium (in two units) with an integrated brine duct system. The energy fence deliminates the garden behind the house southwards and consists of bent U-shaped, plastic coated aluminium sheets with an extruded section is glued to their central portion as a brine duct. Achievements: The heating system was monitored for two seasons: September 1982 to May 1983 ; September to May 1984, during which heat pump output and it's COP of 2.3 failed to meet manufacturer's projections. This is attributed to the fact that the evaporator heat exchanger surfaces were poorly adapted to the condensor, a mis-match causing high temperature differentials between the brine and evaporation temperature, and the condensation and heating water temperature. A better matching of the heat exchangers may increase COP by as much as one point. The energy stack operated satisfactorily, in accordance with the manufacturers specifications, and was found to the be the most durable component of the heat pump system. Energy savings for the demonstration period are equivalent to 7.2 TOE. The planned construction of a second multifamily unit, to be supported by the heat pump will increase annual power consumption from 27,000 kWh to 41,000 kWh and, in combination with tax benefits in Germany, will reduce the payback period to 4.5 years. Single Family Building. The heating system operated from October 1982 to April 1983 and from October 1983 to May 1984. Throughout the demonstration, the heat pump supplied the heating requirements for all the houses (except for a few instances of minor problems with the pump e.g. leakage in the refrigerator circuit). One of the two heat pumps was particularly problematic and had to be replaced. The other operated very well, reaching a COP of 2.8 during the second season. The energy fence was problem-free and easily met the manufacturer's output projections. Operating costs for heating the house were reduced by almost 50 per cent, dropping from DM 3,760 to DM 2,020. Annual fuel oil substitution was equivalent to 1.74 TOE for an electricity consumption of 6,900 kWh. The average COP per heating period was 2.2.