摘要 |
A burner comprising a primary mixing chamber having one or more gas inlets and one or more primary air inlets; and one or more secondary mixing chambers, a perforated portion being provided in a side wall of each of said secondary mixing chambers, and each of said secondary mixing chambers communicating with the primary mixing chamber; each primary air inlet 6 comprising an aperture in a wall of the primary mixing chamber and a sliding member attached to the primary mixing chamber over the aperture and movable between a first limit position when the aperture is completely covered by the member and a second limit position when the aperture is completely uncovered by the member, means being provided to retain the member at any position intermediate the first and second limit positions.
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