Pipes that distribute a heating medium lose some heat to the surroundings. This heat loss causes undesired cooling of the medium in the pipes. The heat loss may be acceptable if the pipes are placed within a heated space. However, this form of heat transfer is undesirable, as it cannot be regulated and may not be required for most of the year.
Heat loss from pipes can be minimised by insulation and by adjusting the medium temperature in relation to the outdoor temperature. The amount of insulation required depends on the water temperature and annual operating hours of the pipes.
Heat loss can also occur when circulating very cold media. In such situations, the pipes are insulated to prevent the media from being heated by the surroundings, and to prevent condensate or frost forming on the external pipe surface.
District heating distribution pipes lose a considerable amount of heat. The loss can be up to 20–25 % of a district heating systems total heat load, which can severely affect the profitability of the system.
Grundfos ensures the lowest possible optimal temperature operation for minimal heat loss in pipe flow in district heating applications.
Pipes carrying hot media are insulated to minimise unintentional heat loss. Heat loss will cool the media while heating the room in which the pipe is located. Both are undesirable.
Considerations to take when insulating pipes are pipe type, the pumped media and the surrounding environment. Pipes carrying cold media and placed in heated rooms are insulated so as not to heat the media and to prevent condensation on the pipe. The insulation insures that the external surface temperature on the insulation is higher than the room’s dew point temperature. The insulation must be finished with a vapour-proof membrane such as aluminium foil or plastic. This is to ensure that room humidity does not penetrate the insulation and condense.
If a pipe is constructed in a flammable material, insulation can protect it against fire so it can remain functional during a fire. This is especially relevant if a plastic pipe supplies a fire protection system further down the line.