Problem:
Rumbling equipment disrupts business, annoys customers, and keeps homeowners awake.

Solutions:
If a building is flexible, stiffen structure or vibration will be unstoppable. Then, address the mechanical systems:

• Use straight ducts within 10 diameters of fans (if space permits) to decrease turbulence.
• Use generously sized pipes and ducts (noise increases relative to velocity to the 4th power).
• Use spring isolators - install isolators (not neoprene pads) on large motors, if not an inertial base.
• Bolt down or remove internal isolation when equipment is set on external isolators (to avoid resonance).
• Clean and balance large fans at least once a year. Do not hang ceiling grid from piping or mechanical units.
• In open offices, add some white noise to minimize the disruption of nearby phone calls and conversations.
• Consider anti-microbial duct linings – new linings have smooth, cleanable, anti-microbial coatings and still absorb high pitched noise.
• Use insulation with a mass-loaded vinyl cover over ducts at large air handlers.
• Use flexible sealant around penetrations to isolate pipe vibration and stop noise passing from room to room.
• Replace old, buzzing fluorescents with new lights with electronic ballasts. For offices, get a fixture with built-in indirect lighting and solve glare problems at the same time.

Additional information:

	HVAC Toolbox - HVAC acoustics: links and tools
	Netwell Noise Control - Sound control products
	Qwyatt - Controlling HVAC Noise
	SOTA - Vibration Isolators - An explanation of vibration isolator deflection from a Canadian firm, State of the Art Acoustik, Inc.

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