In 2018, 28% of energy consumption occurred in domestic building systems. As fuel costs rise, having an efficient and cost effective heating system is one of the main steps to reduce greenhouse gas emissions. Switching to a lower carbon fuel or novel technology to produce hot water offers an alternative way. Phase Change Material (PCM) can be used as heat storage media for a latent heat thermal energy storage system because of its high energy density. In the current application, some PCMs are used as the heat store material with the advantages of self-nucleating properties, high heat of fusion, safe and non-reactive. This paper will indicate a novel domestic hot water (DHW) system. In this technology, various PCM materials have been simulated and tested in DHW systems. PCMs temperature rises when absorb heat. At the time PCMs reach the melting temperature (phase change temperature), they absorb large amounts of heat at an almost constant temperature. Some tests have been done to show the water heating efficiency. According to the water temperature changing record, the highest water temperature was 42.8 °C in the test; and also, in this test, water rose up to the highest temperature in 21 minutes. In the charging process, the lowest melting temperature was 58 °C to melt all the PCM crystal. In the copper coil PCM container unit test, the highest out let water temperature was 44 °C, while the inlet water temperature was 12 °C. The result showed there isn't enough residence time in the coil leads to not enough heat transfer area for it to reach the maximum temperature. The biggest struggle at the moment is to fully access the latent heat of the PCM because of its poor thermal conductivity.