MCC (Mid-Cooling Connection): What it is and how it works
Why return temperature matters in district heating
District heating is one of the most sustainable ways to heat buildings in Sweden. For the system to operate as efficiently as possible, the return temperature must be kept low. A high return temperature means wasted energy, while a low return temperature allows district heating companies to produce heat more efficiently and with less resource use.
What is an MCC district heating substation?
MCC stands for Mid-Cooling Connection and is an innovative solution developed by HögforsGST. It is designed to lower the return temperature in district heating systems and ensure that the energy in the system is fully utilized.
What makes MCC unique is that it’s not just a theoretical concept, it’s a fully developed, ready-to-install solution integrated directly into our MCC district heating substation. The technology is built into the substation’s design, making it easy to benefit from its advantages.
An MCC district heating substation provides:
- Lower environmental impact
- Lower return temperature in the district heating system
- More efficient energy use
- Reduced costs for property owners
How MCC works in practice
In a traditional district heating substation, the district heating water is used to heat both domestic hot water and the building’s heating system. Once that process is complete, the water is returned to the district heating network, often still quite hot. This means that not all available energy has been utilized, leading to unnecessarily high return temperatures.
With the MCC district heating substation, the process is much smarter:
- Step 1: High-temperature district heating water ensures that the domestic hot water reaches the correct temperature for hygiene and comfort in the final heating stage. During normal operation, either preheated water or domestic hot water circulation enters this stage, and the hottest available district heating water is used here.
- Step 2: If the temperature of the district heating water leaving the final heating stage is still higher than the return temperature of the heating system, a three-way valve is activated to further cool the water in the heat exchanger for the heating circuit. This occurs frequently during the day, for example, at night. During nighttime, when hot water usage is low, the domestic hot water circulation still needs to be maintained, and there may be over 50°C available for several hours.
- Step 3: Finally, the already-cooled district heating water is directed into the preheating stage of the domestic hot water heat exchanger. When hot water is being drawn, this stage extracts the remaining heat energy from the water. The cold water entering the system is preheated by the remaining temperature available after the previous steps.
The result is a significantly lower return temperature, often up to 10°C lower than in conventional district heating substations. This means that the energy is utilized to its fullest extent before the water is returned to the district heating network.
Benefits for property owners and district heating companies
An MCC district heating substation delivers value to everyone involved:
- Property owners: Lower flow fees and improved energy efficiency
- Energy companies: A more stable network and reduced production costs
- The environment: Less fuel consumption and reduced CO₂ emissions
MCC district heating in Sweden
MCC is already being used in housing cooperatives, rental properties, and large buildings across Sweden. The technology has been installed in Sweden’s largest housing association improves energy efficiency with MCC in Gothenburg, where results show clear improvements in both operational stability and energy efficiency. Experience shows that the MCC district heating substation contributes to lower energy consumption, more stable temperatures, and a more sustainable district heating system.
Summary:
HögforsGST’s MCC district heating substation is a modern solution for energy-efficient district heating. By lowering the return temperature, it improves both building performance and the efficiency of the entire district heating network, an investment that benefits both the economy and the environment.
MCC District Heating Substation
