Ortech Y-H2 Operation & Installation Instructions page 22

 Fix the lower chimney with 2 4 x 8 mm screws.
 Sliding the chimney to adjust the chimney height. When the height you required is
reached, then fix 2 4 x 8mm screws into the "Plate I" holes as shown below.
 Drill 2 x 8mm holes to accommodate the "Plate II". Screw and tighten the plate into
the wall with 2 screws provided.
 Assemble the chimney into the unit and fix it with 2 screws.
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