A burner 100 comprising a burner body 110 having a burner chamber with a backing plate 122 and having a burner element received in the burner chamber, the burner element having a plurality of gas nozzles 117 for supplying gas into the burner mounted therein for rotational movement such that the direction of gas exiting the gas nozzle can be adjusted. The burner is characterised by means for rotating the gas nozzles 117 are provided on the backing plate 121 and by releasable means for retaining each gas nozzle 117 in a plurality of rotational configurations provided outside the burner chamber. The burner allows for tuning of gas flow from outside the burner while it is in use.
