SOUND CONTROL for AIR DUCTS, HVAC - CONTENTS: 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.
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Noise & sound control for air conditioning or heating system ductwork:
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.
HVAC Duct Insulation Options for Soundproofing & Noise Reduction in buildings
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.
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.
A loud BANG or THUD or CLUNK heard when the heating or air conditioning blower fan starts or stops is often due to inadequate return air, to overpressureizing of the supply plenum at fan start-up, or it may occur where large areas of un-supported sheet metal are used in the duct system or air supply or return plenums. The problem may be more acute where a multiple speed or high speed blower fan is in use.
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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: firstname.lastname@example.org
Sound Oasis sound conditioners are produced by Sound Oasis: http://www.sound-oasis.com/ email: email@example.com or 1-866-625-3218
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Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. 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.
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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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