UnderAire Crawl Space Exhaust Fan w/ Dehumidistat, 110 cfm


Brand: Tjernlund

Mfr Part#: V1D

Availability: In Stock
Usually ships: within 1 business day
Qty Price
$85.95 / each
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Tjernlund V1D UnderAire Fan Powered Crawl Space Exhaust Ventilator quickly reduces moisture helping to protect both home and occupants.


Ventilates excess moisture, the cause of mold, mildew and wood rot. Increases air circulation to fight condensation.

Constant operation helps vent radon, treated wood offgassing and odors that might otherwise migrate into living areas.


The Tjernlund V1D features one fan and large faceplate sized for ventilation openings through block foundations.


Choosing between V1D and V2D it is needed first to determine the number of UnderAire Ventilators:

Calculate the cubic area of the crawl space by multiplying the length x width x height. Divide this number by 15 to determine the minimum CFM necessary to fully ventilate the space in 15 minutes.


Example: 20' wide x 40' long x 3' high crawl space = 2,400 cubic ft. 2400 cubic ft. ? 15 minutes = 160 CFM of ventilation. Choose two V1D ventilators or one V2D ventilator.




Facts to know about Crawl Space Ventilation:


From Mississippi State University Extension Service:

If soil is damp, as much as 20 gallons of water per 24 hours can evaporate into the air in a 1,400 sq. ft crawl space.


Primary causes of excess moisture include:

- Surface runoff water;

- Poor ventilation;

- No or poor ground vapor barrier;


Signs of excess moisture in crawl space:

- Soil is wet;

- Surface organism growth on floor joists;

- Wet insulation;

- Musty odors in crawl space or living areas;

- Excessive moisture in living areas tending to migrate towards windows;


  • Includes adjustable dehumidistat;
  • Thermostat deactivates fan below 40F to avoid freeze-ups;
  • Galvanized face plate may be trimmed if necessary;
  • Has 6' grounded power cord;

Technical Specifications:

  • Number of Fans: 1;
  • Performance: 110 CFM;
  • Motor: 115/1/60, 0.30 amp;
  • Dehumidistat: OFF/ON or 20-80% RH;
  • Thermostat: Opens at 40F;
  • Dimensions: 18" x 9" x 2";
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