This study investigated a novel idea of combining an organic component erythritol with an inorganic component MgCl2 center dot 6H(2)O to prepare new PCMs suitable for domestic water heating. A DSC analysis indicated that mixtures containing less than 20 wt% MgCl2 center dot 6H(2)O have melting temperatures above 353 K and latent heat values greater than 120 kJ/kg. Thermal cycling of erythritol-based PCMs in test tubes showed good stability in terms of nucleation temperature. However, the erythritol-based PCMs were found to undergo supercooling of about 50 K below the melting temperature, similar to erythritol. An analysis of the distribution of the salt hydrate component in the solid phase in a scale-up experiment revealed the salt hydrate's possibility of accumulating at the bottom of the unit. The effect of ultrasonic irradiation on prevention of component segregation was also demonstrated.