Storage Flue Gas Heat Recovery Systems SFGHRS
A Storage Flue Gas Heat Recovery Systems (SFGHRS) is a type of flue gas recovery system (FGRS), or more accurately flue gas heat recovery system (FGHRS) that 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. If the FGHRS contains a volume of water (or condensate), it is known as a Storage Flue Gas Heat Recovery System (SFGHRS).
The UK government document "Review of the methodology for FGHRS in SAP. Final report" describes the systems thus:
"In such devices the store of water is heated by the flue gases via the heat exchanger. This volume of water may be contained in the same unit around the flue, or in a cylinder next to the primary FGHRS unit. The store may be insulated, depending on the store location and the manufacturer’s design. SFGHRS can transfer heat either when the boiler is operating in hot water mode or when the boiler is operating in space heating mode. When the boiler is operating in hot water mode the transfer of heat takes place directly from the flue gas to the incoming water.
"When the boiler is operating in space heating mode the energy must be stored and transferred at a later time, when the boiler switches over to DHW mode. This can either be achieved by residual heat in the body of the FGHRS, or more often via the stored water (acting as a thermal store) within the SFGHRS. The savings that are achieved through the transfer of heat directly to the incoming cold water are known as direct savings and the savings that can be transferred from the flue gas, via an internal store and then to the incoming cold water are known as deferred (or indirect) savings. SFGHRS can provide both direct energy savings and deferred savings whilst Instantaneous FGHRS (IFGHRS) provides predominantly direct savings (although there are still some indirect savings from the water and metal work comprising the IFGHRS)."
[edit] Related articles on Designing Buildings
- Air conditioning.
- Back boiler.
- Biomass boiler.
- Boiler efficiency.
- Boiler.
- Carbon monoxide.
- CHP boiler.
- Coefficient of Performance CoP.
- Combustion appliance.
- Combination boiler.
- Condensing boiler.
- District energy.
- Domestic micro-generation.
- Exhaust air heat pump.
- Fluepipe.
- Geothermal pile foundations.
- Gross calorific value.
- Heat exchanger.
- Heat interface units.
- Heat pump.
- Heat recovery ventilation.
- Heat recovery for buildings.
- Heat source.
- Hot water.
- Heating.
- HVAC.
- Mechanical ventilation.
- Mechanical ventilation's role in improving indoor air quality.
- Refrigerants.
- Tempering heating.
- Types of boiler.
- Types of heating system.
- Types of heat exchanger.
- Variable refrigerant flow.
- Waste heat.
- Waste water.
- Zero Bills Home.
Featured articles and news
UKCW London to tackle sector’s most pressing issues
AI and skills development, ecology and the environment, policy and planning and more.
Managing building safety risks
Across an existing residential portfolio; a client's perspective.
ECA support for Gate Safe’s Safe School Gates Campaign.
Core construction skills explained
Preparing for a career in construction.
Retrofitting for resilience with the Leicester Resilience Hub
Community-serving facilities, enhanced as support and essential services for climate-related disruptions.
Some of the articles relating to water, here to browse. Any missing?
Recognisable Gothic characters, designed to dramatically spout water away from buildings.
A case study and a warning to would-be developers
Creating four dwellings... after half a century of doing this job, why, oh why, is it so difficult?
Reform of the fire engineering profession
Fire Engineers Advisory Panel: Authoritative Statement, reactions and next steps.
Restoration and renewal of the Palace of Westminster
A complex project of cultural significance from full decant to EMI, opportunities and a potential a way forward.
Apprenticeships and the responsibility we share
Perspectives from the CIOB President as National Apprentice Week comes to a close.
The first line of defence against rain, wind and snow.
Building Safety recap January, 2026
What we missed at the end of last year, and at the start of this...
National Apprenticeship Week 2026, 9-15 Feb
Shining a light on the positive impacts for businesses, their apprentices and the wider economy alike.
Applications and benefits of acoustic flooring
From commercial to retail.
From solid to sprung and ribbed to raised.
Strengthening industry collaboration in Hong Kong
Hong Kong Institute of Construction and The Chartered Institute of Building sign Memorandum of Understanding.
A detailed description from the experts at Cornish Lime.























