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Oil burner noise, odor, performance or smoke troubleshooting:
Some oil burner noises are normal, others indicate trouble - we explain the difference.
We also explain how to recognize & diagnose the cause of oil fired heating boiler noises, leaks, odors, or soot and smoke.
We describe just about any noise that you might hear at or near an oil burner, where it comes from, what it means, and what needs to be done about it.
We discuss: What oil fired heating system noises are abnormal and may indicate an operating problem or an unsafe condition? What can we do to reduce heating system operating noises? Diagnose & repair oil burner soot, puffback, rumbling, hard-starting.
Cause & cure for heating boiler "snap, crackle, & popping" noises: antifreeze acidified & debris in the system: flush out needed. Oil burner noise: rattling oil burner motor sounds - "combustion ventilator"? Flue gas exposure hazards, smells, odor. How to diagnose loss of heat, heating boiler noises, leaks, odors, or smoke.
Combustion air fan noise: The combustion air blower, usually a squirrel cage fan on oil burners is spun by a shaft extending out of the
oil burner's electric motor.
The blower itself produces noise as it spins and moves air into the combustion chamber.
Unless the oil burner blower is damaged you probably won't hear it over the other noises produced at the burner.
Warm air furnace blower noise: Furnace blower fan units: A bad furnace fan blower motor or assembly may produce noise you would indeed hear above the noises coming from
the oil burner itself.
Heating oil pump noises: The oil burner's heating oil pump or "fuel unit" is usually driven by a shaft (and couplings) which begin at the electric
motor on the oil burner, extend through the combustion air blower, and connect to a drive shaft protruding from the oil pump.
Unless there is an internal problem with the pump, these units are pretty quiet compared with other normal oil burner noises.
But a pump may whine, rattle, buzz, or make other funny noises when something is wrong.
Draft inducer fan noises: A flue vent connector-mounted or chimney-mounted combustion gas vent draft inducer fan if one is used, is usually audible, and
in a typical installation you'll hear this fan turn on up 15 seconds or so before the oil burner itself begins to operate.
Oil burner combustion noise: Oil burner flame or combustion noise is usually the loudest "normal" noise coming from an oil burner.
The fuel unit pumps
heating oil to 100 psi or higher, then sprays it through an oil burner nozzle where the oil is ignited by electrodes mounted
in the oil burner's tube at the entry to the combustion chamber. The "roar" that you hear at a normally operating heating
system oil burner is usually produced mostly by this combustion process.
Watch out: if you hear a "bang!" sound when the oil burner is starting that may indicate the ignition of accumulated unburned fuel in the combustion chamber. If you have not already had a messy and destructive puffback one is quite possibly imminent. The need for oil burner service is urgent and the system may be unsafe.
Watch out: if you see soot or smoke or smell combustion gases, possibly accompanied by an increase in oil burner or heater noise, the system is not operating properly and may be unsafe.
High speed oil burner noise compared with low speed oil burner noise: High speed oil burners noises: older traditional oil burners used on heating boilers and furnaces were driven by an electric
motor spinning at 1725 rpm.
Modern "high speed" heating system oil burners usually run at 3450 rpm. The higher speed permits
more air flow and greater oil burner efficiency. But in buildings where an older low-speed oil burner is swapped out for a
new "high speed" oil burner unit, the occupants are often surprised to hear that the new equipment is noticeably noisier than
the old unit.
This is normal, and your heating installer would have been smart to tell you to expect this change so you don't
think something's wrong with the new heating system. You're tolerating more noise for lower heating system operating costs.
George Lanthier (Fuel Oil News) reported on customer complaints about the increase in noise when new, more energy efficient but noisier oil burners are installed. In a 2006 article in that publication he offered several suggestions of which his first is that oil companies should "scare the dickens out of the customer" meaning that the vendor should prepare the client for an increase in heating system noise level.
Oil burner mechanical noise: Break the noise levels down by area in the equipment: is the noise from the burner itself?
He argues that the burner mechanical parts are pretty quiet (barring a bad bearing or motor-DF);
Oil burner flame noise: draft conditions can affect flame noise, but Lanthier skirted the basic fact that doubling the burner speed along with concomitant higher oil and combustion chamber pressures increase noise levels. Careful selection of oil burner nozzle, flame retention head and head settings may reduce this noise a bit.
Switching to intermittent oil burner ignition (most residential burners run the igniter all during burner operation) may reduce burner flame noise and also reduce NOX emissions. A service tech can test for this benefit by installing a jumper to permit temporary turn-off of the ignition circuit once flame is established. (Appropriate safety controls must also be installed).
Hollow-cone oil burner nozzles may reduce flame noise. Indeed we (DF) recall from oil burner service days that changing the oil burner nozzle to a flame type and pattern that better matched the burner and combustion chamber could make a large difference in how the burner and flame behaved and sounded. We had good success at reducing rumbling noises at older oil burners by changing to a Monarch AR oil burner nozzle of the proper size.
Measure the system standard heating tuneup parameters including smoke and CO2 to verify that your adjustments have improved, not hurt, system performance. We often found better combustion efficiency using hollow-cone oil burner nozzles -DF.
Chimney noise: In Lanthier's opinion this is the most serious noise problem from heating systems. Certainly we'd agree that many chimneys act as sound amplifiers and transmitters through a building. But Watch out for chimney fires: a roaring freight train sound that means a deadly dangerous fire is occurring (more likely with a wood-stove).
More on chimneys is at CHIMNEYS & CHIMNEY FIRES. Steps to reduce chimney noise, assuming we don't have a dangerous condition, include:
Install a chimney liner (have this done by a professional, certified chimney service company) to reduce noise, condensation problems, and oversized flues that may create venting and even safety problems. See NFPA31-2001, National Fire Protection Association and read all of Appendix E, “Relining Masonry Chimneys” .
Litman chimney elbow: Lanthier describes an idea from Roger Litman (North Shore Fuel) who adds an elbow at the end of a flue pipe run in the base of a chimney to reduce chimney noise. The elbow both reduced noise and improved chimney draft, perhaps because the elbow adds length and thus velocity to incoming chimney vent products. Add a drainage hole in the low point of the elbow, and "get the outlet of the elbow to angle about 15 degrees to the base".
Watch out: Too-Quiet Chimneys can mean big trouble: Lanthier explained that a blocked chimney flue can reduce heating system noise below normal levels, but of course a blocked chimney is dangerous, risking a fatal carbon monoxide poisoning condition as well as improper and unsafe heating boiler or furnace operation and damaging the burner itself (backpressure-burning off the burner end).
What oil fired heating system noises are abnormal and may indicate an operating problem or an unsafe condition?
Noises & soot buildup can lead to a potentially dangerous puffback which can damage the heating equipment and blow soot and smoke throughout the building.
An experienced heating service technician may recognize the following diagnostic list of heating system or oil burner noises as well as perhaps other signs of trouble:
Chimney fires: WATCH OUT: DANGEROUS, IMMEDIATE ACTION NEEDED: Very loud noise like a roaring freight train coming from a chimney is likely to be a
chimney fire- extremely dangerous, risking a house fire: turn off heat as you run out of the house: call the fire department from your cell phone or from a neighbor's house.
A chimney fire moves fast, loud, and produces lots of smoke.
In fact a quick look at the chimney serving a heater at any time can tell you how the heating system is operating.
If the chimney top shows smoke or soot (without the freight train noise of a chimney fire) the burner is not operating properly.
Watch out: If you have a chimney fire (or any kind of fire) stop reading this Internet article, leave the building immediately, and call your fire department.
Banging Noises during oil burner startup - a "bang" or puffback which blows soot into the room through the barometric damper or through other equipment openings: the oil pump may not be shutting down properly at the end of
an oil burn cycle, leaking incompletely burned oil into the combustion chamber. That oil ignites at startup causing a potentially dangerous puffback. Immediate service and repair are needed.
Watch out: an oil burner puffback not only creates a horrible mess, it is dangerous. The puffback can cause the flue vent connection between oil fired appliance and chimney to separate, sending sparks and combustion gases into the building - risking a fire as well as possible dangerous carbon monoxide gas release.
More Oil Burner Startup problems: noises and clues of puff back: if you see flapping at the barometric damper or if you see or hear vibrations in the system, prompt service is needed
and because humming sounds at oil fired heating equipment can originate at or be transmitted by the heating oil piping, see OIL LINE BUZZ & VIBRATION CURE
Noises during oil burner startup - a "rumbling" sound (which usually continues all during operation" or a "stumbling" sound in the combustion chamber probably indicates that the system needs inspection and cleaning very soon.
Some noise is normal however, but the normal sounds tend to be more smooth and continuous. Also
see OIL BURNER RUMBLING NOISE
Noises during oil burner shut-down - a stumbling or rumbling after the oil burner motor has stopped, indicate that oil is continuing to leak into the combustion chamber and risks a dangerous puffback - see "Noises during oil burner startup" above. Immediate service is recommended.
Oil burner motor or fuel unit noises of shrieks or grinding coming from the electric motor or oil pump on the oil burner mean that immediate service is needed - probably a bearing is failing. Beckett (1989) noted that excessive oil burner motor noise may be due to excessive motor shaft end play.
Furnace noises of shrieks, whining, or grinding coming from the electric motor or blower assembly of a furnace air handler probably mean that the system has a bad bearing (or fan belt) and prompt repair service is needed. It's best to shut down such a system since
certain failures, such as sucking a furnace filter into the blower assembly, can lead to overheating and cause a fire.
Noises from radiators or heating baseboards: clanking pipes or sharp snapping noises may be heard as a normal consequence of expansion of metals during the heating cycle. These noises can often be eliminated or reduced
by careful routing of piping and by allowing room around heating pipes for expansion, but probably not eliminated in the case of hot water baseboards.
Bubbling or rumbling noises in hot water heating piping can be caused by air in the heating lines. If the amount of air becomes excessive the
system may be unable to circulate hot water and extra steps to bleed unwanted air will be required.
Hissing sounds such as air escaping from
radiators or other piping where air bleeder valves are installed are normal but should be brief and uncommon. If you constantly hear air
hissing from radiator bleed valves double check that you understand what kind of heat you have - hissing from bleeder valves on steam
heat radiators as heat is coming up in the building is normal.
Noises from Oil Tanks or Oil Piping: Vibrations of the heating oil piping, especially if installed passing overhead along building framing and if installed without sound isolation can use the ceiling as a giant speaker and may be quite loud.
Rumbling noises at the oil burner: may be normal, especially if the noise has not changed, and can often be reduced by choice of a different oil burner nozzle. But an increased rumbling noise can be a sign of burner, combustion chamber, or even chimney problems. See "Oil Burner Flame Noise" above.
Vibration and buzzing at oil burners: Common sources of vibration or sources of buzzing vibrating sounds in or close to an oil burner include:
The oil burner electric drive motor bearings,
the oil burner combustion air blower assembly bearings,
inside the fuel unit or oil pump an out of balance internal part or more seriously, a failing fuel unit can produce vibrations that may be transmitted via oil piping (common)
There is also usually a flexible rubber bushing (the coupling assembly) that connects the driving electric motor through the blower assembly to the fuel unit drive shaft. If that part is the problem you're in luck as it's a low-cost repair. (uncommon)
oil burner assembly mounting bolts that are loose (uncommon)
buzzing electrical components: on occasion a failing HVAC control will emit a buzzing sound, often traced to a faulty transformer or relay (common)
What can we do to reduce heating system operating noises?
Heating equipment located well out of occupied space, in an unoccupied basement, for example, are not usually a source of noise complaints in
a building, though there are a few exceptions for which we have suggestions.
Consult your heating service technician first to be sure that the heating system is operating normally and safely, before
attempting any other steps to reduce noises coming from the heating system. Describe the heating system noise you are observing including the following that may help the service expert:
What is the character of the noise: bang, rumble, squeak, hum, hiss, etc.
When does the noise occur: at oil burner start-up, continuously during burner operation, intermittently
How long has the problem been occurring
What visible clues of trouble are evident: soot
What olfactory clues of oil burner trouble are evident: heating oil odors
How to cure vibrations of the heating oil piping or oil tank: re-route piping between the oil tank and the oil burner
to remove any contact points with overhead ceiling framing or flooring; if those contact points are necessary to support the line, be sure
that the oil line is supported with noise-suppressing fittings (we use foam rubber and copper pipe clamps) and that the piping
is well secured.
UNDER-SIZED RETURN AIR DUCTS can cause excessive duct noise since
inadequate return air means the system is "return-air starved" and will suck air into the duct system at any available (and noisy) opening.
Oil Burner Noise Insulation: some of our readers suggest building an insulated box around the oil burner to reduce its noise.
Watch out! If you constrict or reduce the amount of combustion air available to the oil burner it will not operate properly and the system
could become unsafe. Be sure to discuss the design of any noise insulation scheme and its possible effects on combustion air or other heating
system considerations with your heating service technician.
How to prevent oil burner puffbacks: be alert for signs of a developing oil burner puffback situation such as sooty heating equipment operation, heating oil odors, and stumbling oil burner operation. Often a small "bang" at oil burner startup is a sign of a mini-puffback that may be developing into a major BANG that will leave you sorry you waited to call your service technician.
Because puffbacks can be caused by a variety of problems (oil piping line leaks, dirty oil burner nozzle assembly, fuel or combustion air problems, simply failure to maintain the system) a trained service technician is needed.
Articles at this website describe how to inspect, troubleshoot and repair heating and air conditioning systems to inform home owners, buyers, and home inspectors of common heating system defects.
Continue reading at OIL BURNER NOISE DIAGNOSTIC FAQs for additional examples of oil burner noise sounds and their cause, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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Please see OIL BURNER NOISE DIAGNOSTIC FAQs where we include questions and answers about a variety of oil burner noises including snap, hum, rattle, buzz and rumble as well as other smoke and odor questions.
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 Beckett Oil Burners, "Burner Motor Service Facts", Beckett Corporation, Technical Information, 15 June 1989 [copy on file as PDF].
"Noise and Moisture, Using scare tactics” may be necessary when installing a new heating system", George Lanthier, Fuel Oil News, M2MEDIA360, 1030 W. Higgins Road Suite 230, Park Ridge, IL 60068 847-720-5600
02/1/2006. According to Fuel Oil News, George Lanthier owns Firedragon Enterprises and is the author of nine books on oil heating and heating systems. He is a teaching consultant and expert witness on oil heating systems. He can be contacted at 132 Lowell Street, Arlington, MA 02474-2756. His phone number is (781) 646-2584 and he can be faxed at (781) 641-7099. He can also be contacted through his Web site at www.FiredragonEnt.com.
Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
"Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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