Installing district heating

District heating hot water – how it reaches your home
The water is heated up in the district heating plant and pumped through a pipeline into the house. The hot water is then circulated through the radiators, which then heat your home. District heating hot water is also used to heat your hot water tank which in turn supplies hot water to your taps.

Installation of district heating

1. When you install a district heating system you’ll be supplied with either a hot water tank or a through-flow water heater for supplying hot water to the taps.
2. Supply pipe between street and house
   The district heating supply company is responsible for connecting your house to the pipeline in the street. Wherever possible the pipe to the house is channelled underground, which means that only two holes need to be dug – one in the street and a second by the entry point into your house. A heat meter is installed inside the house.
3. Installation of central heating pipes
   The central heating pipes are laid throughout the house. These are normally enclosed in pipe ducts running along the floor, but they can also be routed via the basement or above the ceiling. Your plumbing and heating installer will be able to advise you on the options. Heating pipes are typically 1.5 cm in diameter.
4. Installation of radiators
   New radiators with thermostatic valves are mounted on the wall and connected to the central heating pipes.
5. Installation of hot water tank or through-flow water heater
   Houses with district heating systems have either a hot water tank or a through-flow water heater for supplying hot water to the taps.
6. Installation of district heating substation
   A district heating substation doesn’t take up much space and can be installed in the utility room, basement, entrance hall, or any other suitable location. This is then connected to the district heating pipe and the central heating system.
7. System ready
   Once installed, the central heating system is filled with water and your installer will perform a full system test of all functions. They will then show you how to operate the system.

Definitions and terms

• Supply pipe
  A supply pipe is an insulated, double tube pipe which supplies a house with heat from the district heating pipeline in the street. Double tube pipes consist of 1 flow pipe to carry the hot water into your house and 1 return pipe to carry the water which has been used for heating your house back into the system.
  The pipe is fed into the house to the heat meter, which is installed in the house, and connected to the district heating pipeline in the street.
  
• Heat meters
  There are 2 types of heat meter:
  Cubic volume meter: Measures the amount of district heating hot water that circulates round the house. Measurements are made in cubic metres (m3). 
  Energy meter: Measures the amount of district heating hot water that circulates round the house, and also how much heat is emitted. This method precisely measures how much heat the house uses. Measurements are made in kWh, MWh (1,000 kWh) or GJ (gigajoule).
  
• District heating substation
  District heating substations transfer the heat to the central heating system in the house – with or without the help of a circulator pump. These substations are most commonly installed in the utility room.
  
  There are 3 types of substation:
  Direct connection without mixing loop
  The central heating system is connected directly to the district heating supply pipe. The district heating company’s own pumps circulate the water through the central heating system in the house. Consequently, no circulator pump is required.
  
  Direct connection with mixing loop
  The central heating system is connected directly to the district heating supply pipe, and a circulator pump pumps the water round the house.
  
  Indirect connection through heat exchanger
  The central heating system is totally separated from the district heating system. A heat exchanger transfers the heat from the district heating hot water to your own central heating system.
  
  Contact your district heating company for advice on which solution to choose.
  
• Circulator pump
  Circulator pumps distribute water to the radiators through pipes. The pump you choose should be one of those listed on the Trust’s A-rated pump list (only in Danish), so you can be sure of an environmentally friendly solution.
  
• Hot water tank
  Hot water is stored in a 100-200 litre tank. When you turn on the hot tap, cold water is fed into the tank and heated up over a period of time.
  
• Through-flow water heater
  Cold water is heated up in a heat exchanger as soon as the tap is turned on.