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.



System 18 Efficiency

SAP seasonal efficiency


Rating band

Band A


ManufacturerDimplex Boilers
ModelSystem 18
Fuel TypeGas
Flue TypeRoom-Sealed
FanFan Assisted
Output (kW)18.1 - 18.1
Boiler IDGC No. 41-149-02
Manufactured From/To2008 - current


The Dimplex System 18 is an 'A' rated boiler which has an excellent efficiency of 91.1%.

The System 18 is a Condensing Conventional boiler with a maximum power output of 18.1kw that uses Gas as its fuel source.

As this boiler is 'A' rated it will provide efficient heating and subsequently reduce fuel bills and carbon dioxide emissions.


Similar Dimplex Boilers to the System 18
(Condensing Gas Conventional)

Results ordered by efficiency. Some models may be obsolete.

Dimplex OV 18

91.1% Efficient

Dimplex System 30

90.4% Efficient

Dimplex OV 32

90.2% Efficient

Most Efficient Conventional Gas Boilers

Baxi Solo 15 HE A

91.3% Efficient

Main 15 HE A

91.3% Efficient

Potterton Promax SL 15

91.3% Efficient

Potterton Gold H 15

91.3% Efficient