SCHEDULED MAINTENANCE
26
Induced Draft and Circulation Blowers
The bearings in the induced draft blower and circulator blow-
er motors are permanently lubricated by the manufacturer.
No further lubrication is required. Check motor windings for
accumulation of dust which may cause overheating. Clean
as necessary.
Flame Sensor (Qualified Servicer Only)
Under some conditions, the fuel or air supply can create a
nearly invisible coating on the flame sensor. This coating
acts as an insulator, causing a drop in the flame sensing
signal. If this occurs, a qualified servicer must carefully clean
the flame sensor with steel wool. After cleaning, the flame
sensor output should be as listed on the specification sheet.
Burners
WARNING
HIGH VOLTAGE
Electrical components are contained in both
compartments. To avoid electrical shock, inju
-
ry or death, do not remove any internal com
-
partment covers or attempt any adjustment.
Contact a qualified service agent at once if an
abnormal flame appearance should develop.
Periodically during the heating season make a visual check of
the burner flames. Turn the furnace on at the thermostat. Wait
a few minutes since any dislodged dust will alter the normal
flame appearance. Flames should be stable, quiet, soft and
blue with slightly orange tips. They should not be yellow. They
should extend directly outward from the burner ports without
curling downward, floating or lifting off the ports.
Check the burner flames for:
1. Stable, soft and blue
2. Not curling, floating, or lifting off.
Burner Flame
Test Equipment
Proper test equipment for accurate diagnosis is as essential
as regular hand tools.
The following is a must for every service technician and ser-
vice shop.
1. Thermometers or thermocouple meter (optional) - To
measure temperatures.
2. Multi-Meter - To measure amperage and voltage, to
test continuity, capacitors, and motor windings.
3. Manometer - To measure static pressure, pressure
drop across coils, filters and draft, and to measure in
-
let and manifold gas pressures.
Other recording type instruments can be essential in solving
abnormal problems, however, in many instances they may
be rented from local sources.
Proper equipment promotes faster, more efficient service and
accurate repairs resulting in fewer call backs.
Heating Performance Test
Before attempting to diagnose an operating fault code, run
a Heating Performance Test to determine if the heating sys-
tem is performing within 5% of the BTU input found on the
rating plate of the unit being tested. To conduct a heating
performance test, the BTU input to the unit must be calculat-
ed (see Clocking a Gas Meter). Before clocking a gas meter,
contact your local utility to provide the caloric value (BTU
content) of the natural gas in the area.
It is also important to confirm the airflow (CFM) is within the
temperature rise range (see Airflow Data in spec sheet) and
external static pressure range (approximately 0.5” water col
-
umn). How-to instructions can be found in the service man-
ual under Checking External Static Pressure and Checking
Temperature Rise.
