A wall-mountable spray head unit (11) is described. The spray head unit comprises a rotatable spray head assembly (81, 82; FIG. 9, 83; FIG. 17) which comprises a spray manifold (181, 182; FIG. 9) rotatable about a first axis (17), a spray nozzle (19) supported by the spray manifold and orientated to deliver fire-suppressant material radially in a plane in a plane defined by the first axis and a second axis which is perpendicular to the first axis, and at least one thermal sensor (20).