In the new generation of district heating networks, the lower supply temperature reduces the heat losses in the distribution network, reaching a higher efficiency of the system. However, reduced temperature increases the risk of Legionella contamination in domestic hot water systems. This report aims to give an overview of the technical solutions that can be implemented in low-temperature district heating networks and fulfil the energy and the safety requirements of the users.
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.
We have investigated and specified a solution for low temperature district heating (LTDH) networks to fulfil the heat demand in single-family houses or apartments. We found that in particular, the district heating unit (flat station) is a technology that can guarantee the decentralised production of domestic hot water and space heating with a pre-assembled unit. It reduces the risk of Legionella contamination while fulfilling the heat requirements of the user. The district heating unit must work at the lowest possible temperature and ensure a good temperature difference (delta T), with low return temperature.
In the report, we list solutions available on the market, with technical data and the description of the main features of each solution. The solutions are optimised for low-temperature supply, so that the heat transfer from the primary to the secondary side is optimised.
The report also provides a guideline about the technical installation that can be considered in the two demo-sites that are part of COOL DH project. The solutions presented can be used when no storage or circulation is used on the domestic hot water system.
Since this is a confidential report, you will not find it for download. However, if you are interested in learning more, please contact Emanuele Zilio at COWI: email@example.com