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Heating System Noise Sources

Diagnose & Repair Heating System Noise Problems

POST a QUESTION or COMMENT about how to diagnose and fix heating system noises, rattles, bangs, hisses, clanking, and other sounds

Diagnosing heating equipment noises:

This noise control article discusses the diagnosis and cure of heating system noises, including heating equipment noise, heat piping or ductwork noises, radiator noises, steam pipe banging, and steam radiator vent noise control.

We describe just about every single noise that might come from or have to do with building heating systems.

We describe the heating system noise, where that noise usually originates, and what to do about it. We discuss: Heating System Noise & Sound Isolation methods. Heating System Noise Cause Diagnosis List & Articles. Troubleshooting heating system noises traced to chimneys and vents. Troubleshooting heating system noises traced to thermal expansion/contraction.

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- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Heating System Noise Source Identification & Cure

Heating systems and building heat as a source of indoor noises and sounds includes a huge range of sounds such as air bubbling in piping, shrieks (bearings), bangs (puffbacks), rumbling (air noise, mechanical noise), grinding noises, and other mechanical noises. A complete list of heating equipment noises, causes, and cures is given here.

Watch out: for roaring freight-train sounds from your oil or gas or wood or coal fired heater chimney: indicating a very dangerous chimney fire if your chimney is roaring get everyone out of the building immediately, then call your fire department

Shortcut: use your browser's search feature (Ctrl-F) or (Cmd-F) to search this page for the kind of noise you're hearing, such as "banging" or "vibration".

For a more thorough understanding of heating system noises let's start by noting that fixing or controlling noises traced to building heating systems is divided naturally into these topics:

Photo: relays in heating equipment can be a source of buzzing or humming that means a part is going to fail soon.

[Click to enlarge any image]

Identify the source and cause of noises traced to the heating system or its components.
Some heating system noises are normal and are thus not a worry.
But other heating system noises (rumbling, buzzing, banging) might be a sign that the heating system needs repairs, that it is not operating efficiently (costing more than necessary for heat), or the heating system may be unsafe.
To rule out heating system operating problems, review heating system noises and noise sources given below, organized by type of heating system
Fix the noise if it's due to a defect or problem
We list heating equipment noises by noise description, its cause and cure, below on this page.
For normal but annoying heating noises, isolate noises, or prevent heating system noise transmission through the building.
Once we are confident that the heating system noises themselves are normal, we can focus on keeping those noises out of the rest of the building.
You will still need to identify specific heating system noise sources, since some noise control steps focus on specific heating system installation details.
Once those noise and sound problems have been addressed, normal building noise transmission and sound control measures, such as sound insulation, can be applied to the room where heating equipment is located.
See HEATING SYSTEM NOISE & SOUND ISOLATION

Watch out: while adding sound control barriers and insulation around a mechanical room be sure that you do not interfere with proper combustion air supply or you risk making the heating system work poorly or you may make it unsafe, risking carbon monoxide production and even death.

Complete Alphabetical Index to Causes of Heating Systems

Heating systems and building heat as a source of indoor noises and sounds include air bubbling in piping, shrieks (bearings), bangs (puffbacks), rumbling (air noise, mechanical noise), grinding noises, and other mechanical noises.

Below is an alphabetical list that includes both noise types by noise name and noise sources by equipment name such as "boiler" or "furnace".

Banging or booming sounds: Banging pounding clanking heating pipes or radiators, especially steam heat:
First, because safety is involved, if you have oil heat
see BOILER NOISE SMOKE ODORS - for oil fired heating equipment that could risk a dangerous puffback explosion
Then see BANGING HEATING SYSTEM NOISES - topic home
or see BANGING HEATING PIPES RADIATORS for noisy hot water or steam heat pipes or radiators that bang or creak
or see BANGING BOOMING NOISE DIAGNOSIS & CURE - home - other sources of bangs booms in buildings
Blower fans and air handlers:
can induce vibration into building HVAC ductwork if a vibration isolator or vibration dampener is not installed.
See VIBRATION DAMPENERS for a discussion of devices used to isolate noises produced by HVAC air handlers such as air conditioners and furnaces.
Bubbling or rumbling
heating system noises in hot water heating piping can be caused by air in the heating lines. If the amount of air becomes excessive the heating system may be unable to circulate hot water and extra steps to bleed unwanted air will be required. See
Buzzing sounds and vibration at oil or gas fired heating boilers, furnaces or water heaters can be caused by a variety of problems such as a control cover touching a relay switch, control unit transformer failures, bad motor bearings, or loose mounting hardware.
Details are at HEATING SYSTEM BUZZING NOISE (originating at the equipment itself) and
at OIL LINE BUZZ & VIBRATION CURE originating at or transmitted by the heating oil piping - the oil burner noise is traced to or is transmitted by oil lines & pipes
Buzzing noises from HVAC equipment like air conditioners, heat pumps, heaters are described
at BUZZING SOUNDS sounds from A/C, heat pump or inverter or from other equipment
BUZZING NOISE DIAGNOSIS - topic home
Also see our HVAC equipment noise home: NOISES, HVAC SOUND DESCRIPTIONS where we list all types of noises and sounds since one woman's buzzing is another gal's thumbing or another fellow's banging and crashing.

Chimney noises:
see CHIMNEYS & CHIMNEY FIRES
Watch out: for roaring freight-train sounds - indicating an immediate emergency - a very dangerous chimney fire may be happening - call the fire department and get out of the building.
Wind blowing over a chimney can produce howling or whistling sounds -
see WIND NOISES at BUILDINGS
Circulator pump noises:
circulator pup ms on hot water hydronic heating systems range from quiet to producing a mechanical whine or hum, or if failing bearings, grinding, or if failing electric motor, humming and vibrating.
In our experience Taco-brand circulator pumps are usually so quiet that we can tell that the circulator pump is running only by feeling for a temperature change the pipes entering and leaving the pump.
See CIRCULATOR NOISES for a catalog of heating zone circulator noises & their common causes.
But if a circulator pump and hydronic heat piping contain unwanted air, cavitation in the pump itself due to the presence of air can make a pump abnormally noisy as well as making a bubbling or gurgling sound in the building hot water heating pipes, baseboards, or radiators. Eventually air leaking into a heating system (or low water volume in the hot water heating system) leads to loss of heat.
See AIR-BOUND HEATING SYSTEMS
Also see AIR BLEEDER VALVES for a catalog of air purging procedures for hot water heating systems.
And see AIR SCOOPS SEPARATORS PURGERS for an explanation of the equipment intended to get rid of un-wanted and noisy air in hot water heating systems.
Clanking heating system 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.
See BANGING HEATING PIPES RADIATORS
Creaking popping sounds:
All heating systems can cause creaking or popping noises as heating system and piping or ductwork expand (and contract) through the heating cycle, though meticulous installation or repair can usually stop those sounds.
Thermal expansion/contraction:
Noises associated with thermal expansion or contraction of heating system components may not mean that there is an equipment operating problem.
Hot water baseboard piping or radiator piping makes creaking or crackling sounds as the piping expands or contracts, particularly where piping passes through tight openings in walls or floors.
HEAT LOSS in BUILDINGS can be reduced to reduce thermal movement
Moisture changes can also cause creaking or TICKING NOISES in buildings. See How Low Should You Keep Indoor Humidity to Avoid a Mold Problem discussed
at HUMIDITY CONTROL & TARGETS INDOORS
Flues noises
associated with heating system exhaust, including
- Chimney noises: see CHIMNEYS & CHIMNEY FIRES.
  Watch out: for roaring freight-train sounds - indicating a very dangerous chimney fire If your chimney is roaring get everyone out of the building immediately, then call your fire department
- Draft inducer fan noises, usually on oil-fired heating equipment.
  See DRAFT INDUCER FANS for details.
- Gas burner noises at gas fired heating boilers or furnaces:
  see GAS FLAME & NOISE DEFECTS
Furnace noises -
forced warm air heating or gravity hot air heating noise
see FURNACES, HEATING - noises caused by equipment operating problems
and SOUND CONTROL for AIR DUCTS, HVAC - noises in the duct system
and DUCT SYSTEM DEFECTS
and depending on the fuel your furnace uses see
Gas burner noises in this list
Oil burner noises in this list
Gas burner noises
at gas fired heating boilers or furnaces:
see GAS FLAME & NOISE DEFECTS
Hissing heating system sounds
such as air escaping from radiators or the 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.
See RADIATORS for ROOM HEAT and
See STEAM VENTS if you have steam heat
Hot water heating system noises
See BOILER OPERATING PROBLEMS
BANGING HEATING PIPES RADIATORS
BOILER OPERATING PROBLEMS
and depending on the fuel your furnace uses see
Gas burner noises in this list
Oil burner noises in this list
Humming noises
at heating equipment may be a burner problem, motor problem, transformer or relay problem or something else.
See HUMMING NOISES in BUILDINGS - topic home
Mechanical system components & motors and moving part noises
- Electric motors
  on oil burners or blower fans see ELECTRIC MOTOR NOISE DIAGNOSIS -
  also see BOILER NOISE SMOKE ODORS
- Bearings
  in electric motors or other mechanical devices (whining, grinding, vibrating, maybe humming)
- Blower fans and air handlers:
  can induce vibration into building HVAC ductwork if a vibration isolator or vibration dampener is not installed.
  See VIBRATION DAMPENERS for a discussion of devices used to isolate noises produced by HVAC air handlers such as air conditioners and furnaces.
- Buzzing noises at furnaces, boilers, water heaters
  are discussed at HEATING SYSTEM BUZZING NOISE
- Circulator pumps
  on hot water hydronic heating systems range from quiet to producing a mechanical whine or hum, or if failing bearings, grinding, or if failing electric motor, humming and vibrating.
  In our experience Taco-brand circulator pumps are usually so quiet that we can tell that the circulator pump is running only by feeling for a temperature change the pipes entering and leaving the pump.
  See CIRCULATOR PUMPS & RELAYS
  But if a circulator pump and hydronic heat piping contain unwanted air, cavitation in the pump itself due to the presence of air can make a pump abnormally noisy as well as making a bubbling or gurgling sound in the building hot water heating pipes, baseboards, or radiators.
  See AIR BLEEDER VALVES for a catalog of air purging procedures for hot water heating systems.
  See AIR SCOOPS SEPARATORS PURGERS for an explanation of the equipment intended to get rid of un-wanted and noisy air in hot water heating systems.
- Duct system noises
  include hissing from air movement and rattling or vibration from loose duct components, particularly where metal ductwork is installed. We have also traced "duct noises" to wind noises and to animals in the ductwork: birds, mice, raccoons, even a cat.
  Also see VIBRATION DAMPENERS for a discussion of devices used to isolate noises produced by HVAC air handlers such as air conditioners and furnaces.
- Mechanically driven motors
  such as the oil pump (fuel unit) on oil burners -
  see ELECTRIC MOTOR NOISE DIAGNOSIS
- Oil burner noises:
  could be normal motor noise or could be a sign of serious and even dangerous heating system conditions. Noises at the oil burner may be due to the electric motor, to motor couplings that drive other mechanical parts, or due to oil burner combustion problems.
  See OIL BURNER NOISE SMOKE ODORS for details.
- Radiator Noises:
  Watch out: If the radiator continually makes noises (whistling or wheezing) at the steam vent, there is a problem that needs to be fixed: a bad steam vent, steam piping problem, steam pressure set too high, or boiler oversized for the heating distribution system.
  See our diagnostic articles at RADIATORS.
- Vibration dampeners
  are needed to isolate vibration that occurs in air handlers or blower compartments from building duct work.
  See VIBRATION DAMPENERS for a discussion of devices used to isolate noises produced by HVAC air handlers such as air conditioners and furnaces.
Odors as clues to heating system noises
for gas fired heating equipment
see GAS BURNER FLAME & NOISE DEFECTS
for oil fired heating equipment
see OIL BURNER NOISE SMOKE ODORS
electrically-powered heating equipment can be noisy too -
see NOISE, WATER HEATER for rumbling crackling popping sound diagnosis
heating system malfunctions that result in un-wanted noise may also produce smells -
see ODORS GASES SMELLS, DIAGNOSIS & CURE - home
Oil burner noises:
could be normal motor noise or could be a sign of serious and even dangerous heating system conditions - see both
OIL BURNER NOISE SMOKE ODORS - home
or OIL BURNER NOISE / ODOR DIAGNOSTIC INDEX for details.
Additional noises at the oil burner may be due to a problem with the oil burner fuel unit (oil pump) such as a bad or slipping coupling between the burner drive motor and the fuel unit. Air in the heating oil supply piping can also cause noises in the fuel unit.
Those problems are detailed at OIL BURNER FUEL UNIT.
Oil piping noises:
buzzing or vibrating sounds may be transmitted from an oil burner fuel unit through flexible copper oil lines to the building, especially if the oil lines are hard-mounted to the basement ceiling (the bottom of floor joists for the floor above.
See OIL TANK PIPING & PIPING DEFECTS
Radiator Noises:
Watch out
: If the radiator continually makes noises (whistling or wheezing) at the steam vent, there is a problem that needs to be fixed: a bad steam vent, steam piping problem, steam pressure set too high, or boiler oversized for the heating distribution system.
See our diagnostic articles
at RADIATORS for ROOM HEAT and
see BANGING HEATING PIPES RADIATORS
Rattling noises:
may be due to loose metal parts such as a loose barometric damper or a loose cover on a furnace or boiler or air handler.
Draft inducer fan noises, usually on oil-fired heating equipment, may include rattling or motor noises.
See DRAFT INDUCER FANS for details.
Sizzling noises
Sizzling noises heard at a heating boiler, either hot water or steam, may indicate that the boiler is leaking and needs prompt inspection and repair or possibly even replacement depending on the leak type and source.
Sizzling from a split system air conditioner / heat pump may be heard at the wall mounted unit when the system is in heating mode and may be normal
Steam heat noises:
see STEAM HEATING SYSTEMS - home
and If your steam pipes or radiators are making a horrible hammering, pounding or banging noise,
see BANGING HEATING PIPES RADIATORS.
Steam heat can also produce (normal) hissing sounds as air escapes from steam radiator valves.
See STEAM VENTS
and depending on the fuel your furnace uses see
Gas burner noises in this list
Oil burner noises in this list
Also see HISSING NOISES in BUILDINGS
Steam pipe noises:
see BANGING HEATING PIPES RADIATORS for the causes and cures of banging, clanging, hammering steam pipes as well as sounds from hot water heat piping.
Steam radiator vent hissing or other noises:
steam vents should quiet down after steam has entered the radiator and the radiator and its vent have become hot.
See STEAM VENT NOISE
Thermal Expansion / Contraction Noises at Heating Systems
All heating systems can cause creaking or popping noises as heating system and piping or ductwork expand (and contract) through the heating cycle, though meticulous installation or repair can usually stop those sounds.
Hot water baseboard piping or radiator piping makes creaking or crackling sounds as the piping expands or contracts, particularly where piping passes through tight openings in walls or floors.
Warm air heat:
see Furnaces in this list
Whining, grinding humming:
bearings in electric motors or other mechanical devices (whining, grinding, vibrating, maybe humming)
Zone valve noises:
sometimes a zone valve motor makes a small grinding or whining noise when the motor is operating. In many cases that's normal. If the heating zone valve motor is getting louder we suspect it's failing.

Heating System Noise & Sound Isolation

Examples of steps that reduce noise transmission from heating systems include

HVAC Duct noises: review and fix loose HVAC duct components, check that vibrations from the mechanical systems are not being picked up and carried through the building by metal duct vibration.

HVAC Ducts & Privacy - no kissing in a Baltimore Basement: Sound from any source can also be transmitted between building areas through the ductwork itself.

The author, politely smooching his girl friend in her family basement rec-room, was jolted by her father's sudden loud voice:

"Joanne! time to come upstairs!!" - her dad just shouted down through the air ducts into the basement,

scaring the heck out of the author and leaving the couple to wonder if their private sounds had been transmitted up to Joanne's parents' bedroom.

The heating ducts in the basement rec-room, heated by forced warm air, provided a listening device for worried parents.

Oil piping vibration transmission: as we cite in the article list just below, clamping heating oil piping to the underside of floor joists converts the floor above to a speaker cone to transmit vibrations from the oil burner into the space above.

Mechanical room sound isolation: once specific sound sources have been addressed, what remains is the isolation of mechanical room sounds from the rest of the building. See the sound control articles beginning

at NOISE / SOUND DIAGNOSIS & CURE - home

...

Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

My heat making big sound. What can I do?

Reply:

Anon

Watch out: some very loud noises like a roaring freight train could mean you've got a dangerous chimney fire. If that's the case get out of the building and call you fire department.

Other loud noises could also point to an unsafe heating system. The safest course is to turn the heating system off and call your heating service company for an emergency repair.

For details see the diagnostics in this article.

We have 3 heating zones. One of them we turn the thermostat up and takes awhile just to bring up the temp a degree or two even though I raise it 6 to 8 degrees. Theres also a box(basement) over the main heating pipe that goes to that zone. Theres a buzzing sound coming from the box...does anyone know what the problem is?

Reply by danjoefriedman (mod) -
Pjh

Above in this article, you will find descriptions of and links to details about the various sources of buzzing noises at heating systems.

From your brief note I suspect there is a failing relay or motor in a zone valve.

...

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