Honeywell HR 40 Instructions De Montage Et D'utilisation page 32

4. Inserting or removing the operating unit
1. Turn the retaining bracket on the operating unit until it points upward.
2. Fit the operating unit onto the valve lantern, pushing it on as far as the stop.
The flat surface of the valve lantern must be flush with the operating unit.
3. Turn the retaining bracket on the operating unit until the tip points
rearward.
To remove the operating unit, reverse this sequence of operations.
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