Faster install. Lower installation time. Better seal.
EHG G-3® is a self-sealing gasketed duct system. A triple-lipped EPDM rubber gasket is placed in a groove at the end of the fitting. When the fitting is inserted into the spiral duct, the gasket folds back forming a seal against the inside of the spiral duct and eliminating the need for any sealer.
In order to achieve optimum sealing for all diameters, various gasket sizes are used. The G-3 gasket is made from a material resistant to ozone, UV rays, and temperature fluctuations. A silicone gasket for special applications is also available. The G-3 gasket is rated for temperatures from -20ºF to +212ºF (silicone gasket rated for temperatures from -94ºF to +302ºF).
Advantages during installation
• Quick assembly – no mastic required
• Easy to install, especially where space is limited
• Better ergonomics
• Assembling and adjusting is made easier
• Less need for manual tools
Advantages during use
• Self-sealing gasket provides a tighter duct system
• The ducts are easier to clean and the risk of bacteria growth is reduced
Bring installation to the highest level
• EHG G-3 is offered in a variety of sizes of ducts and fittings up to 60″ in diameter
• Construction materials include
Single Wall Catalog
Double Wall Catalog
EHG G-3 Specification
G-3 Assembly Instructions
Single Wall Tolerance, Gauge, & e-dimensions
Double Wall Tolerance, Gauge, & e-dimensions
EHG G-3 Double Wall
This is where the magic happens. No other manufacturer provides a simpler system for installing double wall ductwork. Compare traditional double wall with EHG G-3 double wall. Our unique double wall gasketed design offers the owner, engineer, and installing contractor benefits of built-in quality and minimum lifetime cost of ownership.
The Unique Design
Double wall ductwork construction consists of perforated liner on the spiral duct, a solid liner on the fittings, a layer of fiberglass insulation, and a solid outer pressure shell. A perforated inner liner is provided on spiral duct (solid on fittings) with a retaining fabric wrapped between the perforated inner liner and the glass fiber insulation. This fabric prevents fiberglass from entering the airstream while providing acoustical attenuation. Both the inner and outer spiral duct is fabricated with spiral lock seam construction and furnished with a recessed inner liner and EHG’s EnergyX™ insulation stop. Fittings are fabricated with the inner shell flush with the outer shell and a foam insulation stop to insure thermal integrity between the duct/fitting connections. The outer shell connection is a gasketed G-3 connection.
1. Fiber fabric – provides sound attenuation and prevents fiberglass from entering the airstream
2. To insure complete coverage, the fiber fabric is manufactured integral to the inner liner as it is applied when the inner liner duct is spun locking the fabric into the lock seam.
3. Foam insulation stop insures the integrity of insulation across the transverse joints
4. Stand-off clips are provided to maintain concentricity of the inner liner/spiral duct and prevent it from slipping. The clips also prevent the crushing of insulation due to the weight of the inner liner resting on the insulation.
5. The single slip fit insures a clean exterior appearance without flanges or sealing mastic.
6. Available with 1 inch or 2 inch insulation thickness.
7. The complete installed system is provided with a 10 year warranty to satisfy ASHRAE Class 3 leakage requirements.
8. EHG’s calibrated manufacturing tolerances ensure that all the ductwork correctly fits and seals on every project.
Options available in the marketplace, other than EHG’s gasketed system, is a double slip fit, single face flange, or a double face flange connection.
1. Double slip fit means that both the connections of the ductwork inner shell and outer shell are slipped over each other. In the process, the installer is responsible for insuring the integrity of the insulation across the joint. The joint will be mechanically connected with screws and sealing mastic will be applied to prevent air leakage.
2. A single face flange is applied to the outer shell only. The inner liner is slip fit as above, however the outer shell is connected by a flange to prevent air leakage. The integrity of the insulation across the joint is still the responsibility of the installer.
3. Double face flange covers both the inner liner and the outer shell. The flanges are mated face-to-face with a sealing gasket inserted between them and then mechanically fastened together.
4. To the best of our knowledge, there are no flange manufacturers that neither rate their flange connection for air leakage nor provide warranties of any kind.
5. Flanges must be “sealed” to the ductwork and is subject to manufacturing or contractor quality control.
6. A flanged connection requires at least 2 inches additional vertical clearance.
Material cost for EHG G-3 with a gasket is approximately 15% – 20% less expensive than factory installed double face flanges. In addition, installation time is approximately 10% – 40% more efficient with the single slip fit versus flanging considering:
1. If flanges are not installed square to the duct and fittings, the ductwork will not be visually straight.
2. A slip fit connection allows for minor adjustments to the ductwork alignment to accommodate minor offsets.
3. If a field cut is required on flanged ductwork, either a slip fit and sealed connection will result, or the contractor will need to order additional flanges to be field installed. It is difficult to remove already installed and sealed flanges particularly if they were tack welded to the ductwork.
4. Flanged connections require the contractor to furnish and install a gasket between the mating flanges.
5. A flanged connection requires more mechanical fasteners than EHG’s slip fit connection.
6. For field installed flanges, the contractor is required to attach and seal each flange to the ductwork.
7. There is no testing or long term documentation for the performance of duct sealing mastic materials to prevent duct leakage.