The content of the article is elaboration of tabular analysis of heat pump “outdoor air-water“ in heating and domestic hot water system in family house. The object of analysis is comparison of conventional system with using gas boiler or electric boiler and application of heat pump “outdoor air-water“. The part of analysis is energy performance of renewable energy source application as well as financial balance of savings in relation to conventional heat sources and pay-back period of investment in heat pump. Pay-back periods are determined for given boundary conditions and they were considered with rise in the price of energy too.