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Musings of an Energy Nerd

A Better Bath Fan Termination for Soffits

A review of the EZSoffitVent

The EZSoffitVent is a plastic termination fitting for bathroom exhaust fans. It includes an integral backdraft damper.
Image Credit: All images: Bath Fan Solutions

Most bathroom exhaust fans are installed poorly. Because of twisted ductwork, improper terminations, and (in some cases) inappropriate backdraft dampers, the actual air flow through the exhaust fan is much less than the fan rating.

In an article called “A Failure That Stalls the Certification of Many Energy Star Homes,” Allison Bailes described an Energy Star builder who installed nine exhaust fans, each rated at 110 cfm. The builder was hoping that these fans would meet minimum program requirements — requirements which call for bathroom exhaust fans to have an air flow rate of at least 50 cfm. When tested, however, only five of the nine fans met the minimum 50 cfm threshold.

Some of the problems with current installation procedures involve old-fashioned sloppy workmanship:

  • Leaky duct seams;
  • Duct diameters that are too small;
  • Convoluted ducts with unnecessary twists or too many elbows.

Other problems aren’t necessarily the installer’s fault:

  • Most fans lack a good backdraft damper. Installing an inline backdraft damper severely restricts airflow, however.
  • In many homes, there is no easy way to route the exhaust duct to an exterior termination. While soffit terminations are tempting — and in many cases closer than a gable-end termination — most existing soffit termination hardware has serious problems.

In my article on bathroom exhaust fans, I recommended against soffit terminations: “Soffit terminations grow icicles during the winter, and allow humid air to be sucked into the attic in all seasons.” I may have to change that recommendation, however, in light of a new type of soffit termination that has been engineered to solve several bath fan installation problems.

The new soffit termination is called the EZSoffitVent (yes, with all the letters smushed together, without any spaces).

Designed for job-site realities

The EZSoffitVent limits the problem of…

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One Comment

  1. Joe Nagan | | #1

    First Professional Grade Installation System
    Martin: Thanks for the review of our new fitting. After years of investigating problems associated with the 'installation' of; and associated 'call backs' with the current selection of soffit mounted vent fittings, I felt it was time to develop a real professional grade installation system. The current selection of soffit terminations do not address the actual building sequence for installing a bath fan, ducting and fitting at a soffit location. This system was developed to solve several problems:
    a) The fan installer can now complete the entire system (pre-soffit) in one trip with lower total cost
    b) A better overall installation leads to better air flow improving customer satisfaction
    c) The built in air-tight damper improves Blower-Door test results and reduces cold weather comfort complaints due to cold air entry at the fan(s)
    d) Soffit discharge location does not require water intrusion protection (flashing) as does roof or wall discharge fittings
    e) Flush discharge grille is aesthetically more attractive than other options
    Spot ventilation in bathrooms is more important now than ever. It's time the process was improved for fan venting at the soffit location. We are currently working on several other new products.
    For more information readers can go to our website:

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