A solar combisystem is to replace a non-solar heating system in a single family house during 2006. It consist of two 60*60 units; a water storage tank and a technical unit. This solar combisystem was developed during the REBUS-project that aims to develop solar combisystem for Nordic conditions. The water storage tank has a solar storage volume and a hot water stand-by volume. The technical unit contains a condensing gas boiler, heat exchangers, pumps, switching valves, expansion vessel and control components. To work optimally, the REBUS solar combisystem needs low temperature strategy (<60°C). Both the solar collector and the natural condensing gas boiler benefit from low temperatures. This is mainly provided by having a low temperature Space Heating system. The Domestic Hot Water draw offs are at high temperature but during short periods. Space Heating is demanded continuously during a larger part of the year and was 85 % of the total annual heating energy consumption year 2005. To get a better understanding of the heating system’s impact on the REBUS solar combisystem, evaluation of measurement data from the single family house heating system was carried out during spring 2006. The interaction between the different components of the heating system was characterized. To get a view of the energy demand, losses and savings, a pre-study of different temperature and flow control strategies that could meet the space heating energy load was done with Trnsys simulations. The evaluation showed the importance of having a good control strategy for interaction between the Domestic Hot Water heating, the gas boiler, correct adjustment of the Space Heating, and the inhabitants living conditions. A bad adjusted heating system might give higher energy consumption and irregular heating. The simulations showed that it is possible to use lower temperature and flow rates and still fulfil the Space Heating load. In addition, the natural gas energy consumption could be reduced by 15%. The solar saving fractions calculated gave a range of 12-16% depending on control strategy.