Buzzing aquastat relay (C) D FriedmanHeating System Noise Problems
Diagnose, & Cure Heating System Noise Problems

  • HEATING SYSTEM NOISES in BUILDINGS - CONTENTS: Building heating system noises, a concise catalog of sources of building heating system noises: lists of causes, cures, and detection methods for heating system noise complaints
  • POST a QUESTION or READ FAQs about diagnosing the source and finding the cure for noises or sounds in or around buildings and their systems
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Building heating system noise troubleshooting: causes & cures of heating system noises & sounds.

These articles discuss building noise control: how to inspect, diagnose & cure heating system noise or sound problems in homes or commercial buildings.

Our page top photo shows investigation of a buzzing heating boiler aquastat relay.

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Heating System Noises & Building Temperature-Change Noises

Circulator pumps (C) Daniel FriedmanOur detailed article series on heating system noises is found at

A quick guide to heating system noise troubleshooting is given just below.

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.


    BOILER OPERATING PROBLEMS if your heat is by hot water.
  2. For steam heat system noises see STEAM HEATING SYSTEMS;

    for warm air heat see FURNACES, HEATING and DUCT SYSTEM DEFECTS.

    Steam heat can also produce (normal) hissing sounds as air escapes from steam radiator valves. If your steam pipes are making a horrible hammering or banging noise,
  3. Since heating system malfunctions that result in un-wanted noise may also produce smells,
  4. 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.
  • Mechanical system components and moving part noises
    • Electric motors on oil burners or blower fans see ELECTRIC MOTOR NOISE DIAGNOSIS -

    • Banging heating pipes, especially steam heat: see BANGING HEATING PIPES RADIATORS
    • 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.
    • 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. -

      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.
    • 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. Also see HISSING NOISES in BUILDINGS
    • 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.
  • Heating flues, chimneys: Noises associated with heating system exhaust, including
  • Sizzling noises from a split system air conditioner / heat pump may be heard at the wall mounted unit when the system is in heating mode. [10]

  • Thermal expansion/contraction: Noises associated with thermal expansion or contraction of heating system components
    • 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, how to determine and calculate heat loss from a building (or heat gain in a cooling climate), how to evaluate building insulation, & how to insulate buildings
  • HUMIDITY: How Low Should You Keep Indoor Humidity to Avoid a Mold Problem


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HEATING SYSTEM NOISES in BUILDINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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