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Return Air Installations − With Plug
This section is used when replacing a return air smoke
detector which is equipped with a 15−pin plug.
1− Install smoke detector as shown in figure 5. Secure in
place using two 1" screws.
IMPORTANT − The bracket is installed in SGA/SCA240 &
288 units only; discard bracket when installing smoke
detector in SGA/SCA036, 060, and 120 units.
3− Connect the smoke detector plug to unit J102.
Return Air Installations − No Plug
This section is used when replacing a supply air smoke
detector which is NOT equipped with a 15−pin plug.
1− Some units have a separate power source for the
smoke detector instead of the main circuit breaker.
Disconnect the 24 volt wires as shown in figure 4.
CAUTION – Transformer has 120 VAC input.
1− Holes in sampling tube must face down-
ward toward unit base.
2− Insert tubes from the back side of the
smoke detector until tubes snap into place.
3− Install the red cap on the end of the sam-
pling tube that is exposed to the air stream.
4− Place magnet on sheet metal close to the
detector.
(discard bracket when instal-
ling smoke detector in SGA/
SCA036, 060, and 120 units)
SMOKE DETECTOR − RETURN AIR INSTALLATIONS
BRACKET
FIGURE 5
Page 4
2− Open the cover of new LD4120 smoke detector.
Remove and discard the 6− and 15−pin plugs and
harnesses.
3– Remove the cover from the old smoke detector. Mark
wires with terminal number if not already marked.
Disconnect wiring from old terminal strip.
4– Route wiring through new LD4120 smoke detector
access hole and connect wiring to according to
terminals shown in table 1. Replace cover.
5– Assemble
smoke
manufacturer's instructions and previous section.
6– Install the smoke detector on the smoke detector
bracket and install the bracket in the unit. Drill new
mounting holes if required.
7– Reconnect the smoke detector wires to the
transformer.
detector
according
to
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