Removed an old oil burner from a Worcester Danesmoor PJ 20-25 and fitted this one straight in. Had to alter the oil line to enter on the LHS and wire in the "switch live" and "lockout light" although this was straightforward. New burner is running quieter and appears to heat the boiler better. Review the You Tube videos on how to "bleed" the incoming oil line before allowing the burner to "fire up" for the first time.