District Heating - The way to the house
After water has been heated in the heating plant it is passed through pipes to the housing units, offices, hospitals, industries, etc. that need heat and hot water. The technique in itself is well tested and not very complicated.
District heating pipes
The pipes used are called district heating pipes. They consist of an internal pipe that carries the heated water, insulated with a layer of polyurethane foam, and an outer pipe or the casing, made of polyethylene. The pipes are available in different materials and dimensions with thick insulation.
The pipes are delivered complete with insulation but a couple of decimeters of pure steel pipe are left at both ends. This is necessary in order to be able to splice the pipes through welding. Requirements on the welder are very specific. The pipes and the welded joints have to withstand a temperature of 120 degrees Celsius and a pressure of 16 bar, equivalent to 16 times the normal air pressure. After welding, the area around the welded joint is filled with polyurethane foam and a coupling sleeve is placed outside the casing pipe.
The district heating pipes are normally buried in the ground, in streets or parks. In some areas, for example in Stockholm and Gothenburg, the pipes are placed in tunnels under ground. In order to circulate the hot water through the system pumps, usually found by the production plants, are used. In district heating grids where there are several production plants, such as combined in large grids and grids with large altitude differences, there are also pump stations.
How warm is the water?
The temperature of the hot water when it leaves the district heating grid normally varies between 70 and 80 degrees Celsius. With cold weather the temperature of the water is increased and very cold days it can be 100-120 degrees Celsius. The temperature of the return water line back to the plant is around 40-50 degrees lower.
To build a district heating grid to meet the demands of operational reliability and long working life is costly. Depending on the dimensions of the lines and local conditions the costs can vary from SEK 2,000 to 12,000 per meter. The industry is working to ensure quality of the grids in order to achieve as long a life as possible. A well constructed district heating gerid can have a life span of up to 100 years.
Source: Svensk Fjärrvärme, www.svenskfjarrvarme.se/
After water has been heated in the heating plant it is passed through pipes to the housing units, offices, hospitals, industries, etc. that need heat and hot water. The technique in itself is well tested and not very complicated.
District heating pipes
The pipes used are called district heating pipes. They consist of an internal pipe that carries the heated water, insulated with a layer of polyurethane foam, and an outer pipe or the casing, made of polyethylene. The pipes are available in different materials and dimensions with thick insulation.
The pipes are delivered complete with insulation but a couple of decimeters of pure steel pipe are left at both ends. This is necessary in order to be able to splice the pipes through welding. Requirements on the welder are very specific. The pipes and the welded joints have to withstand a temperature of 120 degrees Celsius and a pressure of 16 bar, equivalent to 16 times the normal air pressure. After welding, the area around the welded joint is filled with polyurethane foam and a coupling sleeve is placed outside the casing pipe.
The district heating pipes are normally buried in the ground, in streets or parks. In some areas, for example in Stockholm and Gothenburg, the pipes are placed in tunnels under ground. In order to circulate the hot water through the system pumps, usually found by the production plants, are used. In district heating grids where there are several production plants, such as combined in large grids and grids with large altitude differences, there are also pump stations.
How warm is the water?
The temperature of the hot water when it leaves the district heating grid normally varies between 70 and 80 degrees Celsius. With cold weather the temperature of the water is increased and very cold days it can be 100-120 degrees Celsius. The temperature of the return water line back to the plant is around 40-50 degrees lower.
To build a district heating grid to meet the demands of operational reliability and long working life is costly. Depending on the dimensions of the lines and local conditions the costs can vary from SEK 2,000 to 12,000 per meter. The industry is working to ensure quality of the grids in order to achieve as long a life as possible. A well constructed district heating gerid can have a life span of up to 100 years.
Source: Svensk Fjärrvärme, www.svenskfjarrvarme.se/
Navigate here
• General about district heating
• How is it produced?
• Fuels
• The way to the house
• How it works in the house
• Who buys district heating?
This is how it works:
• General about district heating
• How is it produced?
• Fuels
• The way to the house
• How it works in the house
• Who buys district heating?
This is how it works:
