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4.0 MAINTENANCE
If the duct furnace requires stopping to service, follow the section 3.0 on shutting
the duct furnace down and starting up.
4.1 Recommended Maintenance
NOTE: The following recommended maintenance schedule should be followed every 6
months unless otherwise specified below. It is highly recommended to schedule the
maintenance of the equipment in the spring and fall as equipment demands are commonly
most critical after these periods and serve as good prevention practice.
1. Electrical - Check all wiring for loose connections. Check voltage at the duct furnace
(while in operation). Check amperage draw against nameplate rating. All contactors
should be inspected to ensure that contacts are clean and are making good contact. If
contacts are pitted or burned badly, replace contactor points. Single phasing and motor
burnouts may result from bad contacts. Check all fuses and replace blown fuses with
equivalent size and type.
2. Gas Combustion - Check all fittings, valves and lines for leaks. Check the burner; clean
and adjust if necessary. Check the flame sensor; clean if necessary. Check the fuel
supply pressure to the duct furnace and the manifold pressure. Check and clean the
vent screen if necessary. Refer to burner manufacturer’s IOM for servicing the burner.
3. Controls - Clean and recalibrate all controls and check for proper operation. Repair or
replace any controls found faulty. Check all damper controls and balancing points for
fresh air requirements, tighten any linkages.
4. Motor Lubrication - Refer to motor manufacturer for lubrication recommendations. On
motors having grease drain plugs, remove the plugs and operate the motor for 15
minutes before replacing plugs. Do NOT over grease.
Hours of Service
Re-Grease Interval
(Hours / Day)
Up to 7.5 HP
10 to 40 HP
Over 40 HP
Less than 12
5 Years
3 Years
1.5 Years
More than 12
2 Years
1 Year
9 Months
Motors that run in hot or severe dirt or wet conditions, should be greased at least every six
months.
5. Furnace - Furnaces should be inspected at the beginning of heating season, and every
4 months of usage under normal circumstances. If the furnace is exposed to severe
conditions where exposure to dust, soot, or other impurities contained in the air, a more
frequent inspection is recommended.
•
Clean the burner wheel and rotate the wheel to ensure free movement and tightness
•
Check ignition spark and adjust if necessary
•
Inspect and clean ignition electrodes
•
Check flame supervisor relay flame signal
•
Inspect all safety controls and replace if necessary
