Low Voltage Wiring; Connecting Thermostat Wires; Verifying Anticipator Setting; Grounding - Nordyne M1MB 056 Installation Instructions Manual

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.

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!
Thermostat
Red
Rc
R
H
White
W
Green
G
Yellow
Y
Figure 25. Thermostat Wiring For
A/C Ready Models
Recommended T'STAT Wire
Length (Unit to T'STAT)
Thermostat
Wire Gauge
2-Wire
(Heating)
24 55
22 90
20 140
18 225
Table 6. Thermostat Wire Gauge
M1/M5 A/C
Ready Furnace
Red
White
Green
Grey
5-Wire
(Heating/Cooling)
25
45
70
110
15