Hot Water Supply

a source of hot water for residences and public and industrial enterprises to satisfy domestic and production needs; also, the complex of equipment and structures that provide it. Hot water supply systems consist of heat sources, water treatment apparatus, water heaters, pipelines to transport the water, and devices to regulate and control the water’s temperature.

The water provided by hot water supplies in residential and public buildings and in industrial enterprises for their operational and daily needs must be potable and must satisfy the requirements of the All-Union State Standards. The quality of water intended for technical use is determined by the type of production service it will fulfill. Hot water supplies may be either centralized or local (decentralized). In centralized systems, the heat is generated by heat and electric power plants; and the so-called waste heat of industrial enterprises, underground sources, and other sources is also used. The heat is transmitted to consumers through heating system pipelines. The treatment of hot water is carried out at the heat sources themselves and at central heating points or right in the home. In local systems, the source of heat for warming the water is located at the place where the water is used. A centralized hot water supply may be a closed system in which the water is warmed by a heat-transfer medium (water or steam) from heating networks in water heaters that have been installed at central heating points or directly within the home. In hot water supplies built as open systems, the consumer obtains hot water directly from a heating network. This does away with the need to install water heaters in homes or at centralized heating points and lessens the possibility of corrosion in local pipelines. However, the maintenance of a demand level in such systems requires large volumes of water that have undergone preliminary treatment to prevent scaling and corrosion in the pipelines and the heat-transfer equipment. The maximum water temperature in hot water supplies is 75° C and the minimum (at water faucets) is 60° C.

To prevent cooling of the water in hot water supply delivery pipelines, a constant circulation is maintained during low-demand periods with the help of so-called circulation pipelines. In baths and showers there are heaters connected to the circulating system; with these the rooms are warmed and the towels are dried.

In order to even out the high- and low-demand loads and to cut the costs of heat sources, heat exchangers, heating networks, and water treatment, hot water accumulator tanks are used in centralized systems to store the hot water during low-demand periods, for its distribution during high-demand periods. All new residences and public buildings being constructed in the cities and industrial settlements of the USSR, as a rule, are provided with centralized hot water supplies. This also applies to all industrial enterprises.

In a local hot water supply system, the water heaters are installed right at the locations where the hot water will be used (baths, showers, washing machines, production equipment) and are heated by the burning of fuel (gaseous, liquid, or solid) or electric power. These devices usually require considerable expenditures of time and labor for servicing and, as a rule, do not operate continuously.