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Vibration Dampers & Asbestos at the Air Handler AirCondAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Vibration dampers at air handlers - what are they?
• How to identify asbestos cloth at HVAC vibration dampers and air ducts
• Air Conditioning (or Heating) Duct Defects

This chapter of "How to Inspect the Central Air Conditioning or Cooling System" describes the vibration damper connecting the air handler unit supply plenum to the building supply duct and cites cases of asbestos-containing air conditioning or heating duct work that could send asbestos fibers into building air.

Asbestos in or on HVAC ducts (air ducts or heating and cooling ductwork) is a possible hazard for which we provide links to a separate document - see Asbestos Air Ducts and for a more general guide to recognizing asbestos in buildings, see IDENTIFICATION of ASBESTOS in BUILDINGS. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

What is the Vibration Damper Found on Air Handlers for Heating and Air Conditioning Systems?

The "vibration damper" shown in this photograph and at the top of this page is a fabric or rubberized fabric flexible connection used to join the supply air plenum to supply ducts in a building. On a vertical air handler with conditioned air leaving at the top of the unit, you may see this fabric joint at the supply plenum to which the building supply ducts are connected. The purpose of the vibration damper is simple: by providing a flexible link between the air handler itself (a possible source of noisy vibrations) and the building duct work, the installer is reducing the transmission of noise through metal ductwork into the rest of the building when the blower, furnace, or air conditioner are running.

Damaged Vibration Dampers

Inspect the vibration damper to see that it is intact, not torn or damaged. If the blower is running you may feel air leakage around the damper if it is damaged or not properly installed.

Asbestos Fabric in HVAC Ducts as Vibration Damper Material

On older furnaces and some air conditioning systems you may see a white woven fabric used for the vibration damper material. It is possible that this material was made of asbestos fabric [better photos wanted]. If the vibration damper fabric is white or white-gray (un-coated asbestos fabric) or possibly silver (aluminized coated asbestos fabric) and woven of a coarse-woven fabric it may be an asbestos material.

Look at the lower left corner of our close up photo of an asbestos vibration damper at a warm air furnace. See that little black round spot above the "D" in "Daniel" of our (C) notice? That's where a technician has made a hole in the asbestos damper material in order to insert a thermometer to sense air temperature. The fibers released by such minor damage are probably below the limits of detection.

It is easy to distinguish asbestos fabric in the vibration damper from other common damper materials which have been used as other fabrics are more finely woven (see photos on this page) and may be rubberized or coated canvas or on newer systems, vinyl-coated synthetic fabric.

OPINION-DF: Further testing or inspection may be in order, since if indeed asbestos material was used at this location, and especially if it is damaged, it could release asbestos fibers into building air. Do not tear, cut, or damage the material during your inspection.

If the vibration damper is missing, torn, leaky, or is made of asbestos, we recommend that it be replaced with modern materials. In some cases it may be less costly to simply replace an asbestos-suspect vibration damper than to pay to have it tested. However if you want to test the vibration damper fabric, look inside the return plenum to the inside of the fabric. Often we can find an individual thread sticking up above the metal clamp securing the fabric to the metal plenum sides, easily clipped with no damage to the fabric itself.

More Reading:
Asbestos as a duct hazard is discussed at ASBESTOS HVAC DUCTS.
Also see Asbestos: visual identification of asbestos-suspect materials in buildings - a photo guide.
Fiberglass in HVAC ducts is discussed at Types of Duct Work using fiberglass materials and at risk of mold contamination are discussed here.
Mold in the air handler or duct work is discussed at AIR HANDLER UNIT chapter
HOW TO PREVENT MOLD: Correct the Causes of Mold and Prevent Indoor Mold or other indoor environment problems
OPTIMUM INDOOR AIR QUALITY - Air Filter Choices & Placement for Optimum Indoor Air Quality

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

AIR CONDITIONING SYSTEMS
AIR CONDITIONER COMPONENT PARTS
CONTROLS & SWITCHES
A/C TYPES, ENERGY SOURCES
RATED COOLING CAPACITY
AIR CONDITIONER BTU CHART
SEER RATINGS & OTHER DEFINITIONS
OPERATING COST
SYSTEM OPERATION
OPERATING TEMPERATURES
OPERATING DEFECTS
LOST COOLING CAPACITY
COMPRESSOR & CONDENSING COIL
AIR HANDLER UNIT
AIR FILTERS for HVAC SYSTEMS
CONDENSATE HANDLING
CLEANING & Legionella BACTERIA
DUCT SYSTEM DEFECTS
  ASBESTOS HVAC DUCTS
  DUCT ROUTING & SUPPORT
  BALANCING AIR DUCT FLOW
  FIBERGLASS HVAC DUCTS
  FIRE DAMPERS in DUCTWORK
  GOODMAN GRAY FLEXDUCT
  INCREASING RETURN AIR
  LEAKY DUCT CONNECTIONS
  LOCATION OF REGISTERS & DUCTS
  OWENS CORNING FLEXDUCT
  RETURN AIR REGISTERS & DUCTS
  SUPPLY REGISTERS, & ZONES
  Transite Pipe HVAC Ducts
  UNDERSIZED RETURN DUCTS
  UNSAFE DUCT OPENINGS
  VIBRATION DAMPERS
  WET CORRODED DUCT WORK
  ZONE DAMPER CONTROLS
FAN AUTO ON CONTROLS
A/C REFRIGERANTS
A/C DIAGNOSTIC FAQs
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS
CRITICAL DEFECTS
Air Conditioning "How To" Books
FURNACES WARM AIR HEATING SYSTEMS

Technical Reviewers & References

• Daniel Friedman - principal author/editor of the InspectAPedia ^TM Website
• Thanks to Mark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects" section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and home inspection educator.
• Thanks to Jon Bolton, an ASHI, FABI, and otherwise certified Florida home inspector who provided photos of failing Goodman gray flex duct in a hot attic.
• Thanks to Alan Carson, Carson Dunlop, Associates, Toronto, for technical critique and for providing a copy of Carson Dunlop Weldon & Associates Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

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