Industrial Heating Information – Heat Recovery

The collection and re-cycling of what would be wasted or lost heat requires a lower temperature heat sink, where heat is captured and re-utilised.

Recovered heat can be used in a variety of ways:

  • pre-heating of combustion air for boilers
  • hot water generation, including pre-heating of boiler feed water
  • pre-heating fresh air used to ventilate the building
  • space heating
  • drying
  • power generation.

The following are potential sources of wasted heat:

  • A boiler providing space heating or generating hot water
  • Ventilation/air conditioning systems without any means of recirculation or heat recovery
  • Water chiller or other cooling plant rejecting heat to outside
  • Temperature stratification in high spaces (especially where warm air heaters or radiators are used in place of radiant heating)

Where any of the following processes exist, a thorough heat recovery evaluation should be undertaken:

  • Boiler providing heat for any process
  • Steam boiler blowdown
  • Air compressors
  • Hot exhaust air from dryers, etc.
  • Flash steam
  • Process cooling systems heat rejection
  • Heat stored in products leaving the process
  • Heat in gaseous and liquid effluents leaving the process
  • Heat in cooling hydraulic oil systems


The Carbon Trust has published useful heat recovery information with checklist on its website here.