Hot water supply

• Hot water comes to the consumer directly from the general heat supply system . With this connection, the water quality in the water tap and inside the heating radiator (battery) is the same. That is, people consume heat carrier directly. In this case, the heat supply system itself is called open (that is, through the open taps, the coolant flows from the heat supply system).

• Cold drinking water, taken from the water supply, is heated in the additional heat exchanger with network water, and then it is supplied to the consumer. Hot water and heat transfer medium are separated, hot water consumed by people practically does not differ from cold water in drinking qualities (hot water pipes rust faster than cold ones). In this case , the heat supply system is called closed , since it transfers only heat to consumers, but not heat carrier.

• Hot water is heated in a boiler room or central heating station, after which it is supplied to the consumer separately from the heat supply system. Such a hot water system is called independent . It is most often used in low-rise buildings, if the installation of house heaters is economically unreasonable or impossible; however, it lacks the disadvantages of an open system for low water quality. Another advantage of this system is the possibility of separate maintenance and repair of hot water pipelines and heat supply.

In 1986, in the USSR for use in areas located south of 50 ° N building codes for solar hot water installations were approved. ^[3]

DHW schemes are of three types: cumulative, flow, combined (flow + storage). Accordingly, for each type of circuit its own components and circuit solutions are used.

• Accumulative type dhw scheme - as a rule, such a scheme is used for cottage dhw. The analysis of hot water in the house has a periodic peak character, i.e. it is more intense during breakfast, lunch and dinner. As a storage tank, a boiler is used.

• Flow-type dhw scheme - The flow-type dhw scheme is usually used in factories for production lines that use constant analysis of dhw. Different types of heat exchangers ( plate , tubular, etc.) are used as a heating element for hot water supply; however, plate-type heat exchangers have gained great popularity.

• Combined-type DHW scheme - a combined-type DHW scheme (i.e., flow + storage water heaters), as a rule, is used in factories for production lines that use constant and periodic peak DHW analysis. As a heating element of hot water supply, a flow-through heat exchanger is used. The boiler is used as a thermal energy storage device for peak DHW analysis. The heat exchanger is not used in the boiler, since it is more inert than the flow type heat exchanger.

Since Soviet times, the annual shutdown of hot water for preventive and major repairs on heating systems has been a serious problem for many residents of Russia and the CIS countries. At the same time, in a number of EU countries in houses with central hot water supply, such shutdowns are made for a short time. ^[4] In 2017, the Ministry of Construction of Russia had the intention to abandon planned outages of hot water. A technological experiment is planned to be conducted in two Russian cities. ^[five]

In February 2019, Andrei Chibis, Deputy Minister of Construction and Housing and Communal Services of the Russian Federation, said that the time for disconnecting hot water could be reduced to three days after an experiment was conducted in three cities of the country ^[6] .

Russia

Temporary cessation or limitation of hot water supply may be carried out in the event of a scheduled preventive and overhaul. ^[7] During the period of annual preventive repairs, the shutdown of hot water supply systems should not exceed 14 days. ^[8] Other shutdowns of hot water supply systems shall not exceed: 8 hours (in total) for 1 month, 4 hours at a time, in case of an accident at a dead end, 24 hours in a row. ^[9]

The conclusion to the repair of centralized hot water supply facilities is carried out in agreement with the local government. In the case of coordinating the conclusion for repair, the local government is obliged to organize hot water supply in other ways. ^[7]

• JUK magazine. Typical DHW schemes