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Worcester Heatslave 20/25-OSO-GB-L Oil Combi Oil - 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.

Worcester Heatslave 20/25-OSO-GB-L Oil Combi Efficiency

SAP seasonal efficiency82.5%
Rating bandBand C


ManufacturerWorcester Boilers
ModelHeatslave 20/25-OSO-GB-L Oil Combi
Fuel TypeOil
Flue TypeOpen
FanFan Assisted
Output (kW)20 - 25
Boiler IDC16395/1
Manufactured From/To2001 - current


The Worcester Heatslave 20/25-OSO-GB-L Oil Combi is a 'C' rated boiler with an efficiency of 82.5%.

The Heatslave 20/25-OSO-GB-L Oil Combi is a Non-Condensing Combi boiler with a maximum power output of 25kw that uses Oil as its fuel source.

Although a 'C' rated boiler is not as efficient as many other modern boilers it's still pretty good, only a marginal reduction in fuel bills and carbon dioxide emissions would be observed by replacing it.

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(Non-Condensing Oil Combi)

Results ordered by efficiency. Some models may be obsolete.

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