9
Supply Voltage
Supply voltage to the furnace should be nominal 115 volts. It
must be between 103 volts and 127 volts. Supply voltage to the
furnace should be checked with furnace in operation and blower
running. Voltage readings outside the specified range can be
expected to cause operating problems. Their cause MUST be
investigated and corrected.
CONNECT THERMOSTAT WIRES
a.
Insert 24 volt wires through the plastic grommet just
above the control panel.
b.
Connect the thermostat wires to the furnace low voltage
pigtails (see Figure 5).
c.
Connect low-voltage circuit to the wall thermostat.
d.
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.
NOTE: The thermostat should be installed 4 to 5 feet above
the floor on an inside wall which is relatively free from direct
sources of heat or cold drafts. The nominal anticipator setting
is 0.4. (Refer to the thermostat literature for additional infor-
mation.)
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).
Once the furnace is installed check the thermostat anticipator
against the nominal setting of 0.4:
1.
Connect the milliamp meter in series with the “W” circuit.
2.
Energize a call for heat.
3.
Read the value of the milliamps.
4.
Adjust the heat anticipator of the thermostat to the value
read on the milliamp meter.
If the heat anticipator is set too high the furnace may delay in
coming on.
If the heat anticipator is set too low the furnace may cycle
frequently and not provide the desired comfort level.
Figure 6. Line Voltage Field Wiring
T’STAT
Wire Gauge
2-Wire
5-Wire
(Heating)
(Heating/Cooling)
24
55
25
22
90
45
20
140
70
18
225
110
Recommended T’STAT Wire
Length (Unit to T’STAT)
Table 4. Thermostat Wire Gauge
Figure 5. Control Panel (All Models)
To Combustion
Blower or
Flame Roll-Out
Switch
Thermostat Wires
Blower
Plug
On-Off
Switch
On-Auto
Switch
(Heating
Models Only)
To Gas Valve
or Burner
Power
Entry
Furnace
Control Box
Figure 4. Thermostat Wiring A/C Ready Models
Rc
R
H
W
G
Y
Red
White
Green
Yellow
Red
White
Green
Grey
**
To Cooling Unit
Thermostat
M1G A/C
Ready Furnace
Field Supplied
Disconnect Within
Sight of Furnace
Field Supplied
Panel Connector
Field Supplied
Fused Service
Panel
Black (Hot)
White (Neutral)
Green or Bare (Ground)
Black
White
Black
White
Black
White
Field Line Voltage
Wiring
Factory Line
Voltage Wiring
Ground
Ground
Ground
