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.



Classic RS 255P Efficiency

SAP seasonal efficiency


Rating band

Band F


ManufacturerIdeal Boilers
ModelClassic RS 255P
Fuel TypeLPG
Flue TypeRoom-Sealed
FanNo Fan
Output (kW)16.1 - 16.1
Boiler IDG.C.41 387 15
Manufactured From/ToUnknown - current


The Ideal Classic RS 255P is an 'F' rated boiler with a poor efficiency of 72.8%.

The Classic RS 255P is a Non-Condensing Conventional boiler with a maximum power output of 16.1kw that uses LPG as its fuel source.

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


Similar Ideal Boilers to the Classic RS 255P
(Non-Condensing LPG Conventional)

Results ordered by efficiency. Some models may be obsolete.

Ideal Classic FF 350 P

81.8% Efficient

Ideal Classic FF250P

81.7% Efficient

Ideal Classic LX FF250P

81.7% Efficient

Ideal Classic FF 360 P

80.2% Efficient

Most Efficient Conventional LPG Boilers

Ideal Evomax 30P

93.1% Efficient

Dimplex System 18

93.1% Efficient

Dimplex OV 18

93.1% Efficient

Keston K 170P

93.1% Efficient