The Riello 40 G3B diesel / gasoil is a super-reliable burner that has a wide range of output. The 40 works within a range of 19 to 35 KW (65 to 120 BTU) which is usually enough to heat 12 to 18 radiators (more than enough heat for the average UK home). Riello burners are used in the majority of Worcester Bosch, Grant and Warmflow boilers in the 21kW to 33kW range. The 40 G3B will fit most boilers! Check local regulations and with an oil boiler technician if considering a diesel / gas oil (diesel, gasoil, mazout, fioul, gasolio, Heizöl) burner, as you are likely to be restricted to using this type of burner in a non-condensing outdoor boiler with a vertical flue. With over 80 years of experience in design and manufacture, coupled with leading technology and flexible burner design, Riello is the No.1 choice in the UK. You can buy with confidence - this model has proven reliability. The burner comes with an instruction manual, flange, gasket, and braided flexible hose.