Lennox International Inc. G24-200 - Manual (Page 27)

Page 27
Electrical
CAUTION
Electrostatic discharge can affect electronic com-
ponents. Take precautions during furnace installa-
tion and service to protect the furnace’s electronic
controls. Precautions will help to avoid control ex-
posure to electrostatic discharge by putting the fur-
nace, the control and the technician at the same
electrostatic potential. Neutralize electrostatic
charge by touching hand and all tools on an un-
painted unit surface, such as the gas valve or blow-
er deck, before performing any service procedure.
Refer to figure 15, 16, and 17 for field wiring and figures 18
and 19 for schematic wiring diagram and troubleshooting.
1 − Select circuit protection and wire size according to re-
quirements listed on unit rating plate.
2 − Install a separate disconnect switch (protected by ei-
ther fuse or circuit breaker) near the unit so power can
be turned off for servicing.
3 − Make power supply wire connections at unit make-up
boxes (both left and right side boxes are provided).
4 − Install the room thermostat according to the instruc-
tions provided with the thermostat and make connec-
tions according to the appropriate field wiring
diagram. Install a field-provided 150 ohm, 10 watt re-
sistor (Lennox part number P−8−6256) in two-stage
applications when using an electro-mechanical ther-
mostat.
5 − All applications require a control transformer to power
the furnace’s 24 volt circuit. In all applications except
those where a 208/230 volt power supply is used, an
autotransformer is required to power each of the in-
duced draft blowers. These transformer(s) are pro-
vided in the drive kit which has been selected for use
with the furnace. Transformer part numbers and volt-
ages are given in table 10.
Install the transformer(s) in the control box using the
holes pre-drilled for them.
Select a field wiring diagram according to the power
supply voltage and phase being used (see figure 15,
16, or 17), and make the wiring connections between
the transformers and the furnace.
6 − Select a field wiring diagram according to the power
supply voltage and phase being used (see figure 15,
16, or 17), and make wiring connections between the
blower motor and the furnace. The connecting wires
are provided in the drive kit.
7 − An accessory relay (K109) is provided with the
G24−200 furnace. Any accessory with a rated voltage
equal to the supply voltage can be connected to termi-
nal 5" of this relay. The relay is energized with the
blower.
8 − To add an accessory which is energized on a heating
demand (such as a humidifier), a relay with coil wired
to terminal W1" of the TB1 terminal strip must be add-
ed.
9 − The TB1" terminal strip includes a terminal for econo-
mizer connection. See the field wiring diagrams.
10 − Electrically ground the unit according to local codes or,
in the absence of local codes, according to the current
National Electric Code (ANSI/NFPA No. 70) for the
USA or current Canadian Electric Code part 1 (CSA
standard C22.1) for Canada.
TABLE 10
DRIVE KIT TRANSFORMER VOLTAGES AND PART NUMBERS
Furnace
Supply
**Induced Draft Blower Autotransformers Control Circuit Transformer
Drive Kit
Model No.
Supply
Voltage,
Phase,
Frequency
Transformer
Part Number
& (Quantity)
Wiring
Diagram
Designation
Input
Voltage
Output
Voltage
Transformer
Part Number
Wiring
Diagram
Designation
Primary
Voltage
Secondary-
Voltage
DKG24−200−1
120v,
1ph, 60hz
54G5201*
(2)
T3, T13 115* 230*
LB−66256G
(99K0601)
T1 120 24
DKG24−200−2
208/230v,
1ph, 60hz
− − − − − − − − − − − − − − − −
LB−66256G
(99K0601)
T1 208 or 240 24
DKG24S−200−3,
DKG24−200−6
208/230v,
3ph, 60hz
− − − − − − − − − − − − − − − −
LB−66256K
(13H2801)
T1 208 or 240 24
DKG24S−200−4,
DKG24−200−7
460v,
3ph, 60hz
54G5201
(2)
T3, T13 460 230
LB−66256H
(51H7901)
T1 480 24
DKG24S−200−5,
DKG24−200−8
575v,
3ph, 60hz
54G3101
(2)
T3, T13 575 230
LB−66256J
(66J5401)
T1 600 24
*Note − This transformer has a nominal 230 volt output rating and a 460 volt input rating; however, when wired to the furnace as shown in figure 15, a 115 volt input will produce a 230
volt output.
**Note − The induced draft blowers are rated at 230 volts, single phase, 60 hz.