The measured distribution of intensity of radiation from a proprietary type of gas-fired panel has been found to agree closely with the distribution calculated using Lambert's cosine law and assuming the panel to be uniform in temperature. Near to the panel, convective heating modifies this conclusion and the region affected by convection currents is shown. The area parallel to the plane of the panel over which the heating may be taken to be uniform (to at least 90% of the maximum) is never less than 50 cm².