The fact of the fossil fuels ending, their effects on the environment, the transportation-oriented problems with fuels, their incapability of being reproduced, and the rising cost of the fossil fuels help us to realize the need for new sources of energy. In order to estimate the costs and set the economic logic of using solar water heaters, we have studied the properties of a residential apartment. Thus, the geographical and climatologically properties of the city of Mashhad are considered in this paper. This study is conducted using a descriptive-analytic method and a scaling procedure, categorized in progressive researches over the year of 2014. The results show that 16,431 cubic meters of gas will be saved over a one year period. The data analysis was performed using the RETSCREEN software. Based on the analyses, the financial outcomes show that the project is pro-economic. The volume of CO₂ will decrease 178 ton-CO₂ during the collectors’ useful life, and it highlights their considerable influence in reducing the greenhouse gases. Generally, the results confirm that the required warm water will be provided by spending less money using solar water heaters in residencies considering the rising cost of gas and the subside management program.