T.N.F. Engineering supplies Radiant Heating Lehr. T.N.F. Engineering offers wide ranges of metallic conveyer belts, material handling equipments, glass plant equipment, ovens and furnaces etc, I.S. Conveyor & Cross Conveyors, I.S. Conveyor & cross conveyors, single liners & cold end conveyor, turn tables etc. Radiant Heating Lehr is directly heated lehr with heating elements or heating source placed directly into the Lehr tunnel, which heats up the Lehr heating zones by the heat radiated by the heat source.