When you recommend Temp-Vent foundation ventilation products, you can install an automatic, non-powered foundation vent system or electrical powered ventilators.
Specifying a Temp-Vent foundation vent system is simple. All vents are sized to fit 8" x 16" openings with 1” outside frame on each of 4 sides. However, the design of the system and the number of vents required are different for powered and non-powered vents.
The non-powered, Automatic Foundation Vent will open and close automatically using a heat/cold sensitive coil. The louvers open completely at approximately 70°F and completely close at approximately 40°F. Unlike manual vents that can waste energy when no one remembers to open or close them, these vents self-adjust all year long.
Whenever possible, vents should be placed on all sides of the foundation. This will create an intake/exhaust system that delivers a steady flow of air. One vent should be installed for each 8 to 10 feet of foundation wall.
Most building codes require 1 square foot of open ventilation area for every 150 square feet of crawl space. Temp Vent Automatic Foundation Vents have 50 inches of net free area per vent. Therefore, you should install one vent for every 50 square feet of crawl space.
For crawl spaces with polyethylene installed, on 80-90% of the floor, the ventilation requirement changes to 1 square foot of ventilation for every 1500 square feet of crawl space with a minimum of 4 vents installed to provide cross ventilation. For crawl spaces with polyethylene, install at least one vent for every 500 square feet of crawl space.
Installation Tips for Automatic Foundation Vents
Powered Temp-Vent systems are designed for foundations that require a higher rate of airflow and for areas that are difficult to vent. Depending on the model they can move large amounts of air per hour. Designed to run continuously on a low speed, they draw minimal electricity. However, Temp-Vent recommends power vents be fitted with a thermostat and a humidistat to control the operation of the vent.
To determine the correct number of Power Temp-Vents, use the following formula:
1) Multiply the square feet of the crawl space by the height in feet. This gives the number of cubic feet in the crawl space.
2) Multiply the cubic feet in the crawl space by the number of air changes per hour desired (4-6 is the recommendation). This gives the total number of cubic feet of air that has to be moved per hour to produce the desired number of air changes.
3) Divide this number by 11,160 to obtain the number of power vents needed.
4) Install vents to provide air intake on one side of the foundation with the power vents on the other side to create a system of intake and exhaust.
Example: 1500 square foot crawl space x 3 feet high = 4500
4500 cubic feet x 6 = 27,000 / 11,160 = 2.42 Install 3 power vents with intake vents on the opposite side