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AIR CONDITIONING & HEAT PUMP SYSTEMS
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BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
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DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC HEAT, DIAGNOSIS, REPAIR
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
GAS LP & NATURAL GAS SAFETY HAZARDS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL FILL PIPE LEAKS
OIL SPILL CLEANUP / PREVENTION
PLASTIC Plexvent / Ultravent RECALL
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
ZONE VALVES, HEATING
Electric motor motor noise diagnosis: this article describes the causes, diagnosis, cure & prevention of noises traced to the electric motor component of an oil burner, air conditioner, or other electric-motor driven equipment. For oil burners, separately at OIL BURNER NOISE SMOKE ODORS we describe other sources of noisy oil burners. The sketch of an oil burner shown above is provided courtesy of Carson Dunlop Associates.
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How to Troubleshoot & Repair a Noisy Electric Motor (e.g. on an oil burner & some other HVAC equipment)
|1. Motor won't start, hums||If the motor is humming it is probably not running.||
Watch out: if an electric motor hums and won't start, turn it off immediately to avoid further damage or unsafe conditions.
See Table A in ELECTRIC MOTOR DIAGNOSTIC GUIDE. Also check the motor temperature and current draw.
If the electric motor won't start and is is silent , see ELECTRIC MOTOR OVERLOAD RESET
|2. Motor shaft end play||Excessive electric motor noise can be caused by excessive motor shaft end play - the distance the shaft can move in and out of the motor.||
Beckett (1989)  notes that a new electric AC motor will have no more than .035" of movement in and out. Push the shaft all the way "in", and measure its outwards movement. (Automotive feeler gauges can sometimes assist).
If electric motor shaft end play is more than .060" and if noise is a problem, the motor could be suspect.
|3. Motor is improperly mounted or aligned||
Motor vibration noise can be caused by misalignment of the motor due to its mounting position or due to bad shaft couplings to driven devices such as fans or fuel units.
We find this problem also on hot water heating circulator motors.
Realign the motor or replace a bad coupling. - Beckett (1989) 
|4. Electrical phase problems||If the motor is a 3-phase unit running only on one phase there may be an open circuit, blown fuse/tripped breaker, or unbalanced voltages. Any of these conditions can cause motor vibration.||
Check for open circuit, blown fuse, tripped breaker, uneven voltages on the three phases. - Beckett (1989) 
|5. High or unbalanced voltages||Any of these conditions can cause electric motor vibration and noise||
Check wiring connections, transformer, voltages - Beckett (1989) 
|6. Bad electric motor bearings||Bad motor bearings cause vibration at the shaft support at either end of the motor.||
Check for bearing damage (loose, side play, noise, visible damage); Usually motor bearing damage is caused by improper mounting or motor misalignment.
We've seen a whole series of hot water heating system circulator motors that were destroyed and replaced, one after another until finally a more experienced tech noted that the motor mount was askew. Beckett (1989) 
|7. Loose coupling between electric motor and driven appliance||A bad coupling between the motor drive shaft and the driven fan, fuel unit, or other component can cause vibration and noise as well as motor damage.||Replace the bad coupling; If there is a loose sheave, tighten the set screws or replace that component.|
|Adapted & expanded from Beckett (1989)|
Watch out: some noises at HVAC equipment could be a sign of dangerous operation. For example, rumbling, stumbling noisy oil burners, especially accompanied by smoke, or oil smells, could be a sign of pending PUFFBACKS, OIL BURNER. Squealing motors may be traced to failed bearings, overheating, and on occasion the risk of an electrical fire.
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