The transition to low-temperature supply in district heating networks requires new technical solutions to meet the heat requirements of the consumers and guarantee their safety. The new distribution system at the COOL DH demo site in Høje-Taastrup does just that!
The transition to low-temperature supply in district heating networks requires new technical solutions to meet the heat requirements of the consumers and guarantee their safety, mainly in connection to the possibility of Legionella contamination through the domestic hot water system. At the same time, the efficiency of the district heating system must be ensured.
Among the possible solutions, the single-family units (also called flat stations or district heating units) represents a valid technology to solve the problem. It can be placed in every flat (or single-family dwelling) and it can be implemented with or without a central substation. The flat stations can be implemented in multifamily houses as alternative to water tanks, even though in some areas the use of heat tanks persists.
The new heat distribution system applied to the demo case in Høje-Taastrup Municipality has new single-family units (also called flat stations) installed at each house to supply the heat for domestic hot water and space heating. The units are pre-assembled, which ensures an easy installation procedure. Furthermore, since they use an instant heat exchanger to produce the domestic hot water, which is characterised by a small water volume, the risk of Legionella contamination is reduced to the minimum. The district heating unit must work at the lowest possible temperature and ensure a good temperature difference (delta T), with low return temperature. For this purpose, the heat exchanger must be suitable for LTDH i.e. thermally long and with efficient and rapid working control.
The entire report that describes the DH uni/flat station concept and the installations is available for download at the following link: New type of substation to meet the requirements of LTDH