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Boosting a Dryer Vent

Discussion in 'Mechanical Codes' started by jar546, Aug 15, 2019 at 9:23 PM.

  1. jar546

    jar546 *****istrator

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    Yes, this was installed on a dryer vent that was about 36' from the dryer connection to the exterior. This was used as a booster. Thoughts? Code Compliance? You can ignore the non-compliant, upside-down, exposed, paper-faced insulation. That is a topic for another discussion.

    IMG_9906.JPG
     
    #1 jar546, Aug 15, 2019 at 9:23 PM
  2. Msradell

    Msradell Sawhorse

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    It's hard to tell what kind of fan that is. It looks more like a radon exhaust fan than anything else but it could be in HVAC duct booster fan. Either way it's not designed for this purpose. I'd be very interested to know how they are turning it on (manually or automatically) but in either case I'm sure it's not intended for that kind of use. As far as code compliance goes I'm not really sure.
     
    #2 Msradell, Aug 15, 2019 at 10:27 PM
  3. tmurray

    tmurray Sawhorse

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    The other question is is it designed to be in contact with the insulation?
     
    #3 tmurray, Aug 16, 2019 at 7:22 AM
    jar546 likes this.
  4. mark handler

    mark handler Sawhorse

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    #4 mark handler, Aug 16, 2019 at 8:45 AM
  5. mtlogcabin

    mtlogcabin Sawhorse

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    No where in the code 2012 editions does it address booster fans for residential dryer systems. It is a maximum 35 ft length or what the manufacture of the dryer specifies.

    IMC 2012
    504.6.4.2 Manufacturer’s instructions.
    The maximum length of the exhaust duct shall be determined by the dryer manufacturer’s installation instructions. The code official shall be provided with a copy of the installation instructions for the make and model of the dryer. Where the exhaust duct is to be concealed, the installation instructions shall be provided to the code official prior to the concealment inspection. In the absence of fitting equivalent length calculations from the clothes dryer manufacturer, Table 504.6.4.1 shall be used.


    I see the 2018 does allow booster fans. We should have those adopted about January

    M1502.4.4 Dryer exhaust duct power ventilators.
    Domestic dryer exhaust duct power ventilators shall conform to UL 705 for use in dryer exhaust duct systems. The dryer exhaust duct power ventilator shall be installed in accordance with the manufacturer’s instructions.
     
    #5 mtlogcabin, Aug 16, 2019 at 10:18 AM
  6. fatboy

    fatboy Administrator

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    Last time I checked, there were no listed booster fans...….the motors are the problem, so I have been told.
     
    #6 fatboy, Aug 16, 2019 at 10:23 AM
  7. Pcinspector1

    Pcinspector1 Platinum Member

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    The fan support bracket looks legit for a fantech dryer booster fan.
     
    #7 Pcinspector1, Aug 16, 2019 at 10:25 AM
  8. Ty J.

    Ty J. Sawhorse

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    How about the unlisted duct tape as well? If it is listed, the foil side will be marked(labeled).

    M1601.4.1 Joints, Seams and Connections (paraphrased)
    Longitudinal and transverse joints, seams and connections in metallic and nonmetallic ducts shall be constructed as specified in SMACNA HVAC Duct Construction Standards‒Metal and Flexible and NAIMA Fibrous Glass Duct Construction Standards. Joints, longitudinal and transverse seams, and connections in ductwork shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems, liquid sealants or tapes. Tapes and mastics used to seal fibrous glass ductwork shall be listed and labeled in accordance with UL 181A and shall be marked "181A-P" for pressure-sensitive tape, "181 A-M" for mastic or "181 A-H" for heat-sensitive tape.​
     
    #8 Ty J., Aug 16, 2019 at 10:48 AM
  9. Ty J.

    Ty J. Sawhorse

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    #9 Ty J., Aug 16, 2019 at 10:59 AM
    fatboy likes this.
  10. mark handler

    mark handler Sawhorse

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    #10 mark handler, Aug 16, 2019 at 1:01 PM
  11. ADAguy

    ADAguy Sawhorse

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    Anyone concerned about inline obstruction due to lint collection on fan blades? How do you service it?
     
    #11 ADAguy, Aug 16, 2019 at 1:37 PM
    Msradell likes this.
  12. mark handler

    mark handler Sawhorse

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    You must have access, and that is why a bath inline will not work for a laundry vent
     
    #12 mark handler, Aug 16, 2019 at 2:34 PM
  13. ADAguy

    ADAguy Sawhorse

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    agreed
     
    #13 ADAguy, Aug 16, 2019 at 3:14 PM
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