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Radiant RSF 21 E/3S Gas - Boiler Efficiency Ratings

Boiler Efficiency Rating

You can check your boilers rating by selecting it's make and model below. Ratings are based on the SEDBUK Rating which is an indicator of its efficiency when used within an average domestic household, it's a great benchmark for comparing new boilers and also assessing whether your current boiler would be better off being replaced due to low efficiencies.

For new boiler installations call British Gas Boilers on 0800 327 7119 for a no-obligation quote, alternatively visit Boiler Guide to request quotes from independent local and regional heating engineers.

Radiant RSF 21 E/3S Efficiency

SAP seasonal efficiency80.3%
Rating bandBand D


ManufacturerRadiant Boilers
ModelRSF 21 E/3S
Fuel TypeGas
Flue TypeRoom-Sealed
FanFan Assisted
Output (kW)26.6 - 26.6
Boiler IDCE 0694BL3003
Manufactured From/To2000 - current


The Radiant RSF 21 E/3S is a 'D' rated boiler with an efficiency of 80.3%.

The RSF 21 E/3S is a Non-Condensing Combi boiler with a maximum power output of 26.6kw that uses Gas as its fuel source.

Being a 'D' rated boiler it would be worthwhile replacing it with a higher efficiency 'A' rated boiler.

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(Non-Condensing Gas Combi)

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