Guide to HVAC Duct Sound Control in buildings InspectAPedia® -
Principles of heating system or HVAC sound transmission in buildings
How to make a building quiet: blocking heater or air conditioner or duct noises
Sound insulation designs for building mechanical systems
Sound control for building boilers, furnaces, ducts, pipes, and mechanical rooms
This article explains methods and materials used to control heating, ventilation, and cooling duct noises and sound transmission in buildings: how to make a quiet home, office, or place of business using sound isolation for ceilings, floors, walls, plumbing, etc.
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Our building sound control articles begin at SOUND CONTROL in buildings. Other noise and sound diagnosis and control articles are found at NOISE / SOUND DIAGNOSIS & CURE. Our page top photo shows a typical fiberglass lined HVAC duct interior. The gray debris stuck to the fiberglass is usually house dust, comprised chiefly of skin cells and fabric fiber. Sometimes more troublesome debris collects on interior HVAC duct insulation.
HVAC Duct Insulation Options for Soundproofing & Noise Reduction in buildings
As stated in Best Practices Guide to Residential Construction: Use fiberglass ductboard or fiberglass
duct liners to quiet the noises of fans and moving air. Avoid
sharing a common duct between two rooms that need
sound privacy.
Elaborating on some duct insulation considerations: HVAC experts advise us that conventional practice is to insulate the interior of metal ductwork in order to minimize transmission of HVAC equipment sounds throughout a building.
Some fiberglass duct liners are plastic coated and may be able to be cleaned using gentle procedures.
But most common is the use of un-faced fiberglass duct interior insulation, typically treated with a surface resin binder to help reduce movement of fiberglass particles into the air stream.
Our fiberglass lined duct insulation photo (left) shows clean new metal ductwork with a pink fiberglass mat sound and temperature insulation installed on the duct interior. Our page top photo shows that building dust and debris quickly adheres to fiberglass interior duct insulation.
However our work on indoor environmental and air quality topics suggests that from an indoor air quality maintenance view, we prefer to see insulation on the exterior of metal ducts.
That approach permits the ducts to be cleaned, and it reduces the chances of mold growth in the ductwork.
Construction of HVAC ducts from foil-faced insulating board (photo above left) combines sound and temperature insulation with aluminum foil to product ductwork that is quiet and cleanable using gentle methods.
Other steps to reduce HVAC system duct noise in buildings include:
Proper HVAC duct mounting and routing to avoid tight contact with floor framing without use of sound isolating mounts
Selection of the proper air handler blower size and speed
Location of the air handler unit away from occupied space; if constructing a sound-isolated framed-in enclosure for an air handler for heating systems that burn fuel (LP gas, natural gas, oil, wood) be sure that your soundproofing does not prevent provision of safe and adequate combustion air.
An outdoor combustion air supply can permit near total isolation of HVAC equipment from the rest of the building.
Our photo (left) shows a furnace mounted in a mobile home closet. Owners, in an attempt to reduce furnace noise in the adjacent living space, closed off the return air inlet by installing a solid door. Heating output was substantially reduced and heating costs increased by this bad practice.
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Marpac, produces white sound generators, a product that they identify as the Marpac sound conditioner. Marpac can be contacted at http://www.marpac.com/ or contact the Marpac Corporation,
P.O. Box 560 Rocky Point, NC 28457 Phone: 800-999-6962 (USA and Canada) Fax: 910-602-1435 1-910-602-1421 (worldwide), 800-999- or email: info@marpac.com
Sound Oasis sound conditioners are produced by Sound Oasis: http://www.sound-oasis.com/ email: info@sound-oasis.com or 1-866-625-3218
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