Selecting a powered attic ventilator that best fits your needs

Common Challenges

BROAN Solutions

Selecting a powered attic ventilator that best fits your needs.

i. Selecting a powered attic ventilator that best fits your needs

  1. Step 1: Select Electrical Powered or Solar Powered (Refer to Options tab for detailed explanation outlining benefits of each). Once you have determined what power method you will use, follow the steps under each heading for proper selection of specific product.

    1. Electrical Powered Attic Ventilators. Electrical Powered Attic Ventilators (PAV) are categorized by the amount of CFM they produce (cubic feet per minute of air movement).  To ensure you are installing the right PAV for your attic needs it is important to determine the amount of CFM you require to provide adequate ventilation.

      1. Step1: Calculate the Pitch of your roof. Pitch is the angle of your roof, or the RISE in feet for every 12 feet of RUN.  Pitch is determined by measuring the height of the attic (in feet) at a point that is 12 feet from where the roof rafters and the attic floor joists meet.  Example of an 8/12 Roof pitch:  A roof that is 8 feet height at a point 12 feet from where the roof rafters meet the ceiling joists has a pitch of 8/12.

  2. Step 2:  Determine CFM requirements for your attic. Not all products are rated equally.  Ventilation products are not required to be tested for accuracy of performance ratings.  This can result in a wide array of performance claims that are unsubstantiated through testing by an independent lab.   All BROAN PAVs are rated by HVI – the Home Ventilating Institute, a nationally recognized  independent testing agency and authority on ventilation products, for accuracy of performance.  This means you can be assured the published CFM rating we promise is what you realize once it’s installed in your home. The Home Ventilating Institute (HVI) recommends 1 sq. ft. of open air inlet per 300 CFM of fan capacity.  The best location for these air intake vents is under the eaves with direct access to the attic.  Vents for gable installations should be placed at the end of the house opposite the installed ventilator.  Failure to provide these intakes could cause natural-draft gas appliances to backdraft.


  3. Determining the CFM requirements for your attic
     
     Gable Mount Roof Mount
    Roof Pitch   Model
    353
    Model
    35316
    Model
    349BR
    Model
    350BR &
    350BK
    Model
    355BR &
    355BK
    Model
    356BR &
    356BK
    Model
    358
        760/
    1020 CFM**
    1160/
    1600 CFM**
    1000 CFM 1050 CFM 1200 CFM 1600 CFM 1200 CFM
     
    8/12
    or Less
    Light Roof 1085/1460
    sq. ft. Attic
    1658/2285
    sq. ft. Attic
    1490 sq. ft.
    Attic
    1500 sq. ft.
    Attic
    1715 sq. ft.
    Attic
    2285 sq. ft.
    Attic
    1715 sq. ft.
    Attic
     
    Dark Roof 950/1275
    sq. ft. Attic
    1442/1985
    sq. ft. Attic
    1290
    sq. ft. Attic
    1304
    sq. ft. Attic
    1495
    sq. ft. Attic
    1985
    sq. ft. Attic
    1495
    sq. ft. Attic
     
    9/12 Light Roof 1015/1360
    sq. ft. Attic
    1549/2135
    sq. ft. Attic
    1180
    sq. ft. Attic
    1399
    sq. ft. Attic
    1600
    sq. ft. Attic
    2135
    sq. ft. Attic
    1600
    sq. ft. Attic
     
    Dark Roof 880/1185 
    sq. ft. Attic
    1347/1855
    sq. ft. Attic
    1200
    sq. ft. Attic
    1219
    sq. ft. Attic
    1390
    sq. ft. Attic
    1855
    sq. ft. Attic
    1390
    sq. ft. Attic
     
    12/12 Light Roof 570/765
    sq. ft. Attic
    870/1200
    sq. ft. Attic
    782
    sq. ft. Attic
    790
    sq. ft. Attic
    900
    sq. ft. Attic
    1200
    sq. ft. Attic
    900
    sq. ft. Attic
     
    Dark Roof 500/670
    sq. ft. Attic
    757/1055
    sq. ft. Attic
    684
    sq. ft. Attic
    694
    sq. ft. Attic
    790
    sq. ft. Attic
    1055
    sq. ft. Attic
    790
    sq. ft. Attic
     
    15/12 Light Roof 355/385
    sq. ft. Attic
    559/770
    sq. ft. Attic
    501
    sq. ft. Attic
    508
    sq. ft. Attic
    575
    sq. ft. Attic
    770
    sq. ft. Attic
    575
    sq. ft. Attic
     
    Dark Roof 315/425
    sq. ft. Attic
    486/670
    sq. ft. Attic
    427
    sq. ft. Attic
    430
    sq. ft. Attic
    505
    sq. ft. Attic
    670
    sq. ft. Attic
    505
    sq. ft. Attic
    **Higher CFM with Model 433 shutter. Lower CFM with standard wood louver. The Home Ventilating Institute (HVI) recommends 1 sq. ft. of open air inlet per 300 CFM of fan capacity. The best location for these air intake vents is under the eaves with direct access to the attic. Vents for gable installations should be placed at the end of the house opposite the installed ventilator. Failure to provide these intakes could cause natural-draft gas appliances to backdraft.

  1. Step 3:  Installation Method. BROAN offers both surface, or roof mount models as well as gable mount (side of house) installations.   Your decision will depend on personal preference as well as the construction of your roof and attic, and natural obstructions such as trees that would make access to the PAV difficult, or impede the natural flow of air.

    1. Surface Mount PAVs. Mount just as they say, to the surface of the roof. A relatively simple installation involves cutting a circular hole in the roof through to the attic, making the electrical connections, mounting the product, and replacing the shingles (See detailed installation instructions found with each specific product.  It is recommended that a certified Electrician be used for the electrical connections). Surface mount PAVs can be mounted on any roof using standard asphalt-type shingles.

    2. Gable Mount PAVs. Mount to the gable or side of the house near the roof peak.  Gable mount PAVS are best utilized if the roof surface is irregular (tile, cedar shake etc) or where a standard surface mount installation would not be practical.  The opening on the side of the house is usually finished with either a decorative wood shutter that is permanently open to allow for ventilation, or a powered or automatic Shutter that automatically opens and closes when the ventilator turns on and off to prevent unwanted weather from entering the attic.  (See Broan model 433)

  2. Step 4:  Finish. If you’ve selected a surface mount PAV all that is left is to select the color and material of the dome.  BROAN PAV domes are made of either PVC, Painted Steel or Aluminum.  PVC domes are available in either black or brown.  Metal domes are available in painted brown or natural aluminum.

ii. Solar Powered Attic Ventilators. Like their electrical powered cousins, solar powered attic ventilators provide the same benefits to your attic but do it without the use or the cost of electricity.  By the harnessing the power of the sun to cool your attic, you are doing something positive for the environment and saving money at the same time.  BROAN Solar-Powered attic fans operate without fuel, waste or pollution.  And as a solar-powered solution, they may count as points towards green building.  So when you harness the sun to cool your attic you save money on electricity without using any to do it.  That’s green for the environment, and more green in your wallet too.

1: Determine how many solar powered attic ventilators you need. Since the function of a solar powered attic ventilator (SPAV) is the same as a PAV it goes to say the selection process should be the sameit is not. Due to the nature of solar power, determining the CFM delivered from an SPAV cannot be calculated in the same way.  For that reason, the Home Ventilating Institute has not created a standard test for all SPAVs to be based.  Consequently you may find widely varying CFM claims associated with similar size models that may not be backed in scientific lab tests.  A better, universally accepted approach is to determine the square footprint of your attic–NOT THE CUBIC FEET as well as the number of air exchanges per hour (ten times is a common value to use). We feel this is the best way to determine the number of SPAVs required to move enough air to have a positive effect on the ventilation in your attic.

2:  Determine Placement of SPAVs on roof and method of installation. Unlike a PAV where CFM can reach over 1600 cfm, Solar PAVs cannot deliver as high a rate of CFM due to the size constraints of the fan and the solar panel required to drive the power.  Most roofs will require multiple SPAV to reach the appropriate level.   SPAVs can be used on all roofs with the possible exception of a north facing roof or roofs that are completely covered in shade.  But even that can be overcome with the installation of a remote mounted product (See BROAN 355RSO series remote mount SPAV).  On other roofs, the installation will depend upon where the roof receives the strongest sunlight for the longest time.  As a rule of thumb this is usually determined at 4:00pm.   The SPAV should be mounted no more than 24” down from the peak of the roof and as with PAVs require plenty of inlet vents in the soffit or eaves to promote the flow of air.

3:  Determine Installation style. In many, if not most cases, SPAVs can be flush mounted.  Curb-mounted SPAVs are available for homes with tile, shake or flat roofs and gable mounted can be mounted in the gable or side of the house with a low voltage wire connecting to a remote mounted solar panel on the roof.  Unlike PAVs, SPAVs must be mounted where the solar panel will have access to the greatest amount of sunlight,  sometimes that means mounting the fan on the front of the house.  BROAN has solved that by offering a Remote mounted unit.  Remote models allow you to install the bulkier, fan portion anywhere on the roof that might be less conspicuous and thread a low voltage wire through the attic to the section of roof receiving the greatest sunlight.  A flat, solar panel is mounted to the roof where it will receive direct sunlight without being noticed.

4:  Determine Color BROAN SPAVs are designed to match with most popular shingle colors and are offered in black, brown and weathered wood grey.  The UV-enhanced ABS plastic dome will resist fading, marring and scratches.