This paper presents a method. for estimating the useful output of solar heating sys-terns. Heating load calculations, climatic data and various conditions are used in this procedure to estimate the fraction of the monthly heating load supplied by solar energy for a particular system the design procedure presented in this paper referred to the f-chart method. The results of this study are as follows; 1) The collected energy is not rised lineary to collector area. 2) If the heating area has equivalent solar collector area, the solar energy utilization for space heating is over 90%. 3) Transmittance- absorptance product for radiation at normal incidence, (${ au}{alpha}$)/(${ au}{alpha}$)n, during most of the heating season is 0.92 for a two-cover collector. 4) Orientation of the collector has little effect on the annual performance of solar heating system within the $15^{circ}$.