Hitachi RCI Service Manual page 381

12 Maintenance notes
Attach the vinyl sheet to the side plate of the exchanger using
adhesive tape. Seal the gap between the vinyl sheets with adhesive
tape.
Use a brush to clean any dust from the interior surface of the heat
exchanger. To do so, brush downwards and collect all of the dust
in a bucket or cardboard box.
Follow the steps below to hang the cleaning water manifold from
the indoor unit:
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SMGB0063 rev. 1 - 10/2010