Chamberlain Merlin Whisper Drive MT3850 Installation And Operating Instructions Manual page 12

INSTALLATION STEP 4
Position the Opener
Follow instructions which apply to your door type as
illustrated.
Sectional Door (A) or Tracked Tilt Door (B)
You will need a 50mm piece of timber or similar
spacer to gauge the distance between door and rail.
1. Raise the opener onto the support.
2. Open the door completely and place a 50mm
spacer between the door and the rail
(as shown).
3. If the top section or panel hits the trolley when
you raise the door, pull down on the trolley arm
to disengage the opener. Leave the trolley in this
position until opener is fastened in place.
One-Piece Non Tracked Tilt Door (C)
You will need a 100mm (4") piece of timber or similar
spacer to gauge the distance between door and rail.
1. Raise the opener onto the support.
2. Open the door completely and place a 100mm
spacer between the door and the rail as shown.
3. The top of the door should be level with the top
of the opener. Do not position the opener more
than 50mm (2") above this point.
NOTE: Timber spacers should be left in place until
completion of Installation Step 5.
To prevent scratching or marking the garage door, rest garage
door opener rail on piece of wood placed on top section of door.
A
Header
Bracket
Door
B
Header
Bracket
C
Header
Bracket
11
Rail
50mm (2")
above the highest
point of travel
50mm spacer should
be used to determine
the correct mounting
position
50mm (2")
above the highest
Rail
point of travel
Door
50mm spacer should
be used to determine
the correct mounting
position
200mm (8")
above the highest
point of travel
Door
100mm spacer should
be used to determine
the correct mounting
position
Rail