Last edited 14 Nov 2025

Instantaneous Flue Gas Recovery Systems IFGRS

Flue gas recovery systems (FGRS), or more accurately also known as flue gas heat recovery systems (FGHRS) capture and reuse waste heat from exhaust flue gases, these are used to preheat water or other fluids, improving energy efficiency by reducing demand and thus reducing emissions. Where this heat is used immediately on any used fluids it is known as an Instantaneous Flue Gas Recovery Systems (IFGRS). Where the heat captured is storage for later used it is known as a Storage Flue Gas Heat Recovery Systems SFGHRS. Whilst SFGHRS can provide both direct energy savings and deferred savings Instantaneous FGHRS (IFGHRS) provide predominantly direct savings (although there are still some indirect savings from the water and metal work comprising the system.

For further information see the UK government document "Review of the methodology for FGHRS in SAP".

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