This European Standard specifies the requirements and test methods for the construction, safety, classification and marking of non-domestic gas-fired overhead radiant tube heaters incorporated into a multi-burner system (called system D and referred to in the body of the text as the ""system"") with each burner unit under the control of an automatic burner control system.This standard is applicable to Type B52 systems (see 4.3) intended for use in other than domestic dwellings, in which the supply of combustion air and/or the evacuation of the products of combustion is achieved by mechanical means.This standard is not applicable to:a) systems designed for u