Boiler Efficiency Ratings

Compare new boilers and assess whether your current boiler would be better off being replaced

Our boiler efficiency tables provided by SEDBUK (the seasonal efficiency of domestic boilers in the UK) provide a guide of how effective your boiler is at turning fuel into heat.

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 0333 230 5216 for a no-obligation quote, alternatively visit Boiler Guide to request quotes from independent local and regional heating engineers.



35 CDi II RSF Efficiency

SAP seasonal efficiency


Rating band

Band D


ManufacturerWorcester Boilers
Model35 CDi II RSF
Fuel TypeLPG
Flue TypeRoom-Sealed
FanFan Assisted
Output (kW)27.5 - 27.5
Boiler ID47 311 59
Manufactured From/To2001 - current


The Worcester 35 CDi II RSF is a 'D' rated boiler with an efficiency of 80.4%.

The 35 CDi II RSF is a Non-Condensing Combi boiler with a maximum power output of 27.5kw that uses LPG as its fuel source.

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


Similar Worcester Boilers to the 35 CDi II RSF
(Non-Condensing LPG Combi)

Results ordered by efficiency. Some models may be obsolete.

Worcester 28i Junior

81.7% Efficient

Worcester 28 Si RSF

81.4% Efficient

Worcester 25 Si - L RSF

81.1% Efficient

Worcester 25 Si RSF

81.1% Efficient

Most Efficient Combi LPG Boilers

Keston C 36P Combi

92.8% Efficient

Ravenheat Combistore 32 LPG

92.8% Efficient