Lennox GCS16-653-75

Page 57
O-Firestats
Some local codes may require the installation of discharge
air and return air firestats to automatically shut down the
unit when excessive temperature is reached . Other local
codes may require firestats wired to perform tasks such as
energizing a blower or closing dampers. These field pro
vided firestats MUST be mounted and wired per local
codes or insuring agencies. Manual reset controls MUST
be accessible.
Figures 74 and 75 show typical firestat wiring connections.
Figure 74 shows firestats connected inline with transform
er T1 primary. When either or both firestats open, the con
trol circuit is deenergized, the unit shuts down and the
economizer outdoor air dampers drive full closed.
Figure 75 shows firestats connected inline with the 24VAC
control circuit. When either or both firestats open, the con
trol circuit is deenergized while control transformer T1 re
mains energized to operate dampers, exhaust blower, etc.
The unit shuts down and economizer outdoor dampers
drive full closed.
FIGURE 74
LINE VOLTAGE
TO UNIT
L1
L2
L3 (THREEPHASE ONLY)
LINE VOLTAGE
FROM DISCONNECT
24VAC
FIRESTATS
TYPICAL FIRESTAT WIRING
CONTROL TRANSFORMER CUTOUT
FACTORY WIRING
FIELD WIRING
1- Turn off power to unit.
2- Mount and wire firestats per local codes or in
suring agencies. Route wires to main control
box.
3- Route wires away from sharp metal edges
and moving or vibrating components.
F1
24VAC TO UNIT
24VAC
COMMON
FIGURE 75
LINE VOLTAGE
TO UNIT
L1
L2
L3 (THREEPHASE ONLY)
LINE VOLTAGE
FROM DISCONNECT
24VAC
FIRESTATS
TYPICAL FIRESTAT WIRING
UNIT CONTROL CUTOUT
FACTORY WIRING
FIELD WIRING
1- Turn off power to unit.
2- Mount and wire firestats per local codes or in
suring agencies. Route wires to main control
box.
3- Route wires away from sharp metal edges and
moving or vibrating components.
24VAC
COMMON
F1
24VAC TO UNIT