Boilers with a SEDBUK Band Rating of “F” have an efficiency value of between seventy and seventy-four percent (70%-74%). If you have a Standard (non-condensing) GAS Boiler already installed & would like to check it’s SEDBUK SAP rating – please view the complete, full boiler list on the SEDBUK Band F (efficiency rating between 70%-74%) Boiler Ratings Page! HINT: Click the image (on the left!) to read more…