Rheem RGFG Installation Instructions Manual page 36

ELECTRICAL CHECKS
Line Power Check
The furnace must have a nominal 115
volt power supply for proper operation.
If there is not a consistent power sup-
ply, contact a licensed electrician to
correct the problem.
1. With the blower compartment door
off, manually hold the push button
door switch in.
2. Call for heat at the thermostat.
3. With the unit operating, use a volt-
meter to measure the voltage from
any 120 VAC terminal to any neu-
tral connection.
4. The voltage should be a nominal
115 volts (acceptable 105-120VAC).
This test should be made with the unit
in full operation.
Polarity Check
If line & neutral are reversed, a fault
code (26) will be displayed at the fur-
nace seven segment display (SSD)
and at the communicating thermostat
active fault display screen (communi-
cating systems only).
Proper line voltage polarity, or phasing,
is a must for this furnace to operate.
Use a volt meter to make this check.
1. With the blower compartment door
off, manually hold the push button
door switch in.
2. Use a voltmeter to measure the
voltage from any 120 VAC terminal
to any bare metal ground on the
furnace.
3. The voltage should be a nominal
115 volts (acceptable 105-120VAC).
4. Use a voltmeter to measure the
voltage from any neutral terminal to
the bare metal ground on the fur-
nace.
5. The voltage should be less than 1.0
VAC.
6. If the voltage from any 120 VAC ter-
minal to ground is less than 1.0
VAC volts and the voltage from a
neutral to ground is a nominal 115
volts, the polarity is reversed.
7. To correct the problem, either
reverse the hot and neutral wires to
the furnace or have a licensed elec-
trician check the building wiring.
Control Voltage Check
1. With the blower compartment door
off, manually hold the push button
door switch in.
2. Call for heat at the thermostat.
(Does not include communicating
thermostats.)
36
3. With the unit operating, use a volt-
meter to measure the voltage from
control voltage terminal "W" to ter-
minal "C" on the furnace control
board.
4. The voltage should be a nominal 24
volts (Acceptable 18-30 VAC).
This test should be made with the unit
in full operation.