This 39 IN x 13 IN x 28 IN WattsBox insulated enclosure protects backflow prevention assemblies, such as PVBs, double checks, and RPZs, that are subjected to freezing conditions. The enclosure consists of fiberglass construction, providing access through lockable doors and/or a hinged lid for testing and certification purposes. It has a means for a permanent anchor and is completely removable for maintenance purposes. It has drain openings that are protected against severe weather conditions. Thermostatically protects to minus 30 degree F (minus 34 degree C).