MG3P Installation Manual

28
• Electrical connections must be in compliance with all applicable
local codes with the current revision of the National Electric
Code (ANSI/NFPA 70).
• For Canadian installations the electrical connections and
grounding shall comply with the current Canadian Electrical
Code (CSA C22.1 and/or local codes).
IMPORTANT NOTE:
If replacing any of the original wires supplied with the
furnace, the replacement wire must be copper wiring and
have a temperature rating of at least 105°F (40°C). For
electrical specifications, refer to the furnace nameplate or
Table 5 (page 31).
Line Voltage Wiring
It is recommended that the line voltage (115 VAC) to the furnace
be supplied from a dedicated branch circuit containing the correct
fuse or circuit breaker for the furnace as listed in Table 5.
IMPORTANT NOTES:
• An electrical disconnect must be installed readily
accessible from and located within sight of the furnace.
See Figure 41 (page 31) or the wiring diagram label
inside of the control door. Any other wiring methods
must be acceptable to authority having jurisdiction.
• Proper line voltage polarity must be maintained in order
for the control system to operate correctly. Verify the
incoming neutral line is connected to the white wire and
the incoming “hot” line is connected to the black wire.
The furnace will not operate unless the polarity and
ground are properly connected as shown in Figure 41.
Thermostat / Low Voltage Connections
• The furnace is designed to be controlled by a 24 VAC
thermostat. The thermostat’s wiring must comply with the
current provisions of the NEC (ANSI/NFPA 70) and with
applicable local codes having jurisdiction.
• The thermostat must be installed according to the instructions
supplied by the thermostat manufacturer. Low voltage
connections (24 VAC) from the thermostat are wired to the
terminal strip on the integrated control in the furnace. Figure
43 (page 31) contains the proper connections for heating
only (two-wire) and heating/cooling (four-wire) applications.
Recommended minimum wire gauge for thermostat wiring is
shown in Table 5 (page 31).
• The thermostat should be mounted about 5 feet above the
floor on an inside wall. DO NOT install the thermostat on an
outside wall or any other location where its operation may be
adversely affected by radiant heat from fireplaces, sunlight, or
lighting fixtures, and convective heat from warm air registers or
electrical appliances. Refer to the thermostat manufacturer’s
instruction sheet for detailed mounting information.
Single Stage AC & Single Stage Thermostat
This option does not use the full two-stage control capability of
the furnace, but the possibility of timed autostaging is available.
See also Autostaging for Single Stage Thermostats.
• Connect the thermostat’s W output to the furnace control
boards W1 terminal. This allows the furnace to always run in
low output mode. See Figure 38 (page 29).
• Always connect the thermostat C & R to the furnace control
board C & R.
• For cooling, connect the thermostats Y signal to the furnace
control board Y / Y2 terminal.
• Field supplied wires should also connect Y / Y2 & C to the
outdoor unit’s Y & C terminals.
The ignitor may not ignite the gas until all of the air is bled from
the gas line. If the ignition control locks out, adjust the thermostat
to its lowest setting and wait one minute. Adjust the thermostat 5
degrees above room temperature and the ignitor will try again to
ignite the main burners. This process may have to be repeated
several times before the burners will ignite. Once the burners
are lit, check all gas connections for leaks again with the soap
and water solution.
WARNING:
Do not alter or remove the original rating plate
from the furnace.
8. Affix the conversion warning label to the outside of the unit
door and the conversion information label near the rating
plate inside the control area.
9. Affix the gas conversion label from the conversion kit on the
gas valve. Each label should be prominent and visible after
installation.
10. Reinstall the appliance door.
11. Run the appliance through three complete cycles to assure
proper operation.
ELECTRICAL WIRING
WARNING:
ELECTRICAL SHOCK, FIRE OR
EXPLOSION HAZARD
Failure to follow safety warnings exactly could
result in serious injury, death or property
damage.
Improper servicing could result in dangerous
operation, serious injury, death or property
damage.
• Before servicing, disconnect all electrical
power to furnace.
• When servicing controls, label all wires prior
to disconnecting. Reconnect wires correctly.
• Verify proper operation after servicing.
AVERTISSEMENT :
RISQUE DE DÉCHARGE ÉLECTRIQUE,
D’INCENDIE OU D’EXPLOSION
Le non-respect des avertissements de sécurité
pourrait entraîner des blessures graves, la mort ou
des dommages matériels.
Un entretien inapproprié peut provoquer un
fonctionnement dangereux, des blessures graves, la
mort ou des dommages matériels.
• Avant toute intervention, couper l’alimentation
électrique du générateur d’air chaud.
• Pour l’entretien des commandes, étiqueter tous
les fils avant de les débrancher. Rebrancher les
fils correctement.
• Vérifier le bon fonctionnement après l’intervention.