Nordyne Downflow Direct Vent Forced Air Gas Oil Furnaces SERIES M1B - Manual (Page 15)

15
Figure 24. Control Panel (All Models)
On-Off
Switch
Blower
Plug
Power
Entry
On-Auto Switch
(Heating Models Only)
Thermostat Wires
Furnace
Control Box
To combustion
Blower or Flame
Roll-out Switch
To Gas Valve
or Burner
Table 6. Thermostat Wire Gauge
Thermostat
Wire Gauge
Recommended T’STAT Wire
Length (Unit to T’STAT)
2-Wire
(Heating)
5-Wire
(Heating/Cooling)
24 55 25
22 90 45
20 140 70
18 225 110
Connecting Power Supply Wires
1. Remove the furnace control panel cover.
2. Route wires (115 VAC) through the strain
relief on the left side of the furnace control box
(see Figure 24).
3. Connect the hot wire to the black pigtail lead,
and the neutral wire to the white pigtail lead.
Secure all connections with suitable wire nuts.
4. Connect the ground wire to the grounding
screw.
5. Reinstall the control panel cover and secure
with the original mounting screws.
Low Voltage Wiring
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.
NOTE: The thermostat must not be installed on
an outside wall or any other location where its
operation may be adversely affected by radiant
heat from fi replaces, sunlight, or lighting fi xtures,
and convective heat from warm air registers or
electrical appliances. The nominal anticipator
setting is 0.4. (Refer to the thermostat literature
for additional information.)
Five-conductor thermostat wire is recommended
for 24 volt low-voltage circuit (2-wire is required
for furnace only; 5-wire for heating and optional
cooling systems). Refer to table 6 for thermostat
wire information.
Connecting Thermostat Wires
1. Insert 24 volt wires through the plastic grommet
just above the control panel.
2. Connect the thermostat wires to the furnace
low voltage pigtails (see Figure 25).
3. Connect low-voltage circuit to the wall
thermostat.
4. A hole may be made in the furnace cabinet
to ease thermostat wiring. Make sure that the
wiring is protected from the sharp edge of the
added hole.
Verifying Anticipator Setting
After the furnace is installed, check the thermostat
anticipator against the nominal setting of 0.4.
1. Connect the milliamp meter in series with one
of the gas valve’s low voltage terminals.
2. Energize the gas valve.
3. Read the value of the milliamps.
4. Adjust the heat anticipator of the thermostat
to the value on the milliamp meter. If the heat
anticipator is set too high, the furnace may
delay turning on. If set too low, the furnace
may cycle frequently and not provide comfort
to the homeowner.
Figure 25. Thermostat Wiring For
A/C Ready Models
Rc
R
H
W
G
Y
Red
White
Green
Yellow
Red
White
Green
Grey
Thermostat
M1/M5 A/C
Ready Furnace
Grounding
WARNING:
To minimize personal injury,
the furnace cabinet must have
an uninterrupted or unbroken
electrical ground. The controls
used in this furnace require an
earth ground to operate properly.
Acceptable methods include
electrical wire or conduit approved
for ground service. Do not use gas
piping as an electrical ground!