Bypass Sizing Adjustments
The Arzel® Bypass Calculator provides good results for "average systems.  However, individual system characteristics may require adjustment of the bypass damper either one size larger or smaller.
  • Flex Duct - down-size the bypass by one size because of the increased friction loss inherent in flext duct.
  • Distant Zones - Equivalent duct length greater than 200 ft. may require a one-size decrease due to increased friction loss.
  • Close Zones - Equivalent duct length less than 50 ft. may require a one-size increase.
  • Special Purpose Zones - Usage pattern may dictate that some rooms are very quiet (ie. recording studios, nurseries, home offices, etc.) This may require an increase in bypass size.

Other Bypass Rules of Thumb

  • Objectionable Air Noise is the ONLY reason to bypass.
  • Keep the bypass as small as possible. This will maximize air delivery and therefore system effectiveness.
  • Bypass should be at least 8 ft. from the return drop. This provides adequate time and space for the bypass and return air to mix.

Click here to go to the online Arzel®Bypass Calculator

Home | Tools | Products | Education | Tech Info | Contact | Site Map

4801 Commerce Pkwy., Cleveland, OH 44128 | Ph: (216) 831-6068 or TOLL FREE: (800) 611-8312
Copyright 2000-2010 Arzel® Zoning Technology, Inc. All Rights Reserved