Abstract: The present invention relates to environmental control apparatus for telecommunications equipment, and in particular, relates to a radio telecommunications electronics enclosure drain valve. A base station antenna electronics enclosure typically comprises antenna arrangements and associated control cabinets. Whilst ideally the internal space within an electronics enclosure is hermetically sealed, this is not generally possible due to, inter alia, the differential expansion of the different components within the enclosure, the need for access for maintenance purposes, the electrical performance characteristics and so on. The antennas are contained within an antenna enclosure--the enclosures on masts visible to the public. In order to provide a sufficient field of coverage, the antenna should be placed at a height above ground level, typically upon a building or a mast, extending 15 m or more. In such a position, an antenna enclosure is subject to extremes of temperature, windage and moisture.