HVAC system seals and gaskets maintain efficiency by preventing the loss of heated and cooled air. Whether installing new ductwork, modifying an existing system, or just replacing worn out gaskets, it’s important to choose appropriate material. Many HVAC specialists consider neoprene gaskets the default choice, but it’s possible better performance could be achieved with EPDM or silicone gaskets.
HVAC Gasket Applications
Gaskets have three main roles in HVAC systems:
- Sealing opening panels, flaps, and doors
- Reducing transmission of motor or fan vibration
- Allowing for thermal expansion and contraction
Sealing
Almost every ducting system includes access doors and panels, along with dampers that close off airflow through “legs” of the system. To minimize closing forces, these need a soft material with good compressibility. Combined with appropriate thickness, such gaskets will also take up the dimensional variation and uneven edges inevitable in most systems.
Reducing Vibration Transmission
Fans and motors can cause a vibration in flat ducting that’s audible as a low hum. To avoid complaints from building tenants, incorporate gaskets at appropriate interfaces. The cellular structure absorbs the vibration and prevents it spreading throughout a system.
Expansion and Contraction
Metal ducting experiences significant dimensional changes in response to switching between warmed and cooled air. A gasket with good recovery takes up these changes while still maintaining a leak-tight seal.
Environmental Factors
Outdoor applications challenge HVAC gasket material as UV light degrades some materials, and moisture penetration must be avoided. Low temperatures and ozone might also be a concern in some applications.
HVAC Gasket Materials
Neoprene gaskets and those made from thermoplastic elastomers (TPE’s) generally perform when soft and resistant to compression set. EPDM gaskets work well outdoors as they stand up to sunlight and other weathering effects. Where air or gas temperatures are high silicone gaskets can be a good choice.
Closed cell materials may be preferable because air and moisture cannot pass through, although these are firmer, requiring higher closing forces.
Installation is simplified by using a pressure sensitive adhesive (PSA). This can be laminated on to the gasket material or can be applied in tape form.
