Lennox G60UHV Series Installation Instructions Manual page 39

Electrical
1 - Check allwiring forlooseconnections.
2 - Check forthecorrect v oltage at thefurnace(furnace
operating).
3 - Check amp-draw ontheblower m otor.
MotorNameplate Actual
NOTE - Do not secure the electrical conduit directly to the
air ducts or structure.
Electronic Ignition
The two-stage, variable speed integrated control used in
G60UHV units has an added feature of an internal Watch-
guard control, The feature serves as an automatic reset de-
vice for ignition control lockout caused by ignition failure.
This type of lockout is usually due to low gas line pressure,
After one hour of continuous thermostat demand for heat,
the Watchguard will break and remake thermostat demand
to the furnace and automatically reset the control to begin
the ignition sequence,
Flue And Chimney
1 - Check flue pipe, chimney and all connections for tight-
ness and to make sure there is no blockage,
2 - Check unit for proper draft.
3 - Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and outlet
for blockages.
4 - Reset manual flame rollout switches on burner box,
Failure To Operate
If the unit fails to operate, check the following:
1 - Is the thermostat calling for heat?
2 - Are access panels securely in place?
3 - Is the main disconnect switch closed?
4 - Is there a blown fuse or tripped circuit breaker?
5 - Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6 - Is gas turned on at the meter?
7 - Is the manual main shut-off valve open?
8 - Is the internal manual shut-off valve open?
9 - Is the unit ignition system in lock out? If the unit locks out
again, call the service technician to inspect the unit for
blockages.
NOTE - The control board thermostat selection DIP switch is
factory-set in the "TWO-STAGE" position.
Applications Using a Two-Stage Thermostat
A - Heating Sequence -- Control Board Thermostat
Selection DIP Switch in "Two-Stage" Position (Factory
Setting)
1 - On a call for heat, thermostat first-stage contacts close
sending a signal to the integrated control. The inte-
grated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts.The combustion air inducer is ener-
gized at low speed and the 120 VAC humidifier termi-
nal is energized.
2 - Once the control receives a signal that the low pres-
sure switch has closed, the combustion air inducer be-
gins a 15-second pre-purge in low speed.
3 - After the pre-purge is complete, a 20-second initial ig-
nitor warm-up period begins. The combustion air in-
ducer continues to operate at low speed.
4 - After the 20-second warm-up period has ended, the gas
valve is energized on low fire (first stage) and ignition oc-
curs, At the same time, the control module sends a sig-
nal to begin an indoor blower 45-second ON-delay.
When the delay ends, the indoor blower motor is ener-
gized on the low fire heating speed and the 24V hu-
midifier terminal is energized. The furnace will contin-
ue this operation as long as the thermostat has a
first-stage heating demand,
5 - If second-stage heat is required, the thermostat sec-
ond-stage heat contacts close and send a signal to the
integrated control. The integrated control initiates a
30-second second-stage recognition delay.
6 - At the end of the recognition delay, the integrated con-
trol energizes the combustion air inducer at high
speed. The control also checks the high fire (second
stage) pressure switch to make sure it is closed.The
high fire (second stage) gas valve is energized and the
indoor blower motor is energized for operation at the
high fire heating speed.
7 - When the demand for high fire (second stage) heat is
satisfied, thecombustion air inducer is switched to the
low-fire heating speed and the high-fire (second
stage) gas valve is de-energized. The low-fire (first
stage) gas valve continues operation. The indoor
blower motor is switched to the low-fire heating speed.
8 - When the thermostat demand for low-fire (first stage)
heat is satisfied, the gas valve is de-energized and the
field-selected indoor blower off delay begins. The
combustion air inducer begins a 5-second post-purge
period.
9 - When the combustion air post-purge period is com-
plete, the inducer and humidifier terminals are de-en-
ergized. The indoor blower is de-energized at the end
of the off delay,
Applications Using A Single-Stage Thermostat
B - Heating Sequence -- Control Board Thermostat
Selection DIP Switch in "Single-Stage" Position
NOTE - In these applications, two-stage heat will be initi-
ated by the integrated control if heating demand has not
been satisfied after the field adjustable period (10 or 15
minutes).
1 - On a call for heat, thermostat first-stage contacts close
sending a signal to the integrated control. The inte-
grated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts.The combustion air inducer is ener-
gized at low speed and the 120 VAC humidifier termi-
nal is energized,
2 - Once the control receives a signal that the low pres-
sure switch has closed, the combustion air inducer be-
gins a 15-second pre-purge in low speed,
3 - After the pre-purge is complete, a 20-second initial ig-
nitor warm-up period begins. The combustion air in-
ducer continues to operate at low speed.
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