Thermal Stores, as their name suggests, are intended to store heat from various sources, like solid-fuel fired boilers, heat pumps or solar thermal collectors. These are suitably sized pressure vessels designed to store heat from these sources until it is needed to heat a building. Recently, demands for combination of various sources prevail, like solar thermal systems, solid fuel (or biomass) boilers, electric heating etc. For operation with several sources Regulus develops and manufactures its own thermal stores that become a kind of a centre for the entire technology where all these sources are concentrated, supplying energy for both space heating and instantaneous hot water heating. However, hot water can be also heated separately in a dedicated hot water storage tank.