Flex Connections

[Dymalica]

I have a packaged A.C. unit outside with side discharge. What is the best way to isolate vibrations to the duct? I heard flex connections outside can't handle the elements.

 

[VinceNY]

Is any of the duct weatherproofed?

 

[Wareagl487]

Most - if not all - roof mounted air handling equipment manufactured today has its moving parts internally isolated. I make no special provisions for connecting to a horizontal discharge RTU with a flex connection. IMO it is not needed.

Andy W.

 

[hvacinsider]

We never install ductwork to a unit or any other device with a motor without a flex canvas connection. Noise and vibrations are a nightmare. Why not just do it right the first time?

 

[DrRTU]

We connect all horizontal RTUs with a flexible connector for sound and ease of connection. Old rubber coated canvass would not hold up under heavy use and sunlight outside. We build our outside duct (low and medium pressure) with ductmate to a medium pressure class. The flex assembly is fabricated as a small joint. This process allows "slop" in the connection without using a slip sleeve. The use of ductmate and internal conduit stiffeners keeps water ponding down and holdup well when a mechanic stands on the duct. We have used Duro Dyne for years. We have not used the insulated product.

http://www.durodyne.com/xephr/list/DUCT_CONNECTOR

Smaller RTUs do not transmit large amounts of vibration and the exterior duct with thick lining is an excellent attenuator. I like to infill the curb with wall board and foam sheets to minimize compressor and fan noise below the RTU.