How does an automatic foundation vent work?

A bimetallic coil in the frame expands and contracts with temperature, pushing the louvers open in warm weather and closing them in cold. There is no motor, wiring or thermostat to set.

Will it fit my existing vent opening?

It is made for an 8 x 16 inch opening, the common size on older foundations. Measure the rough opening before ordering, since frames that are slightly off will need trimming or shimming.

Does it keep out insects and rodents?

The louvers close when cold but the vent is not a sealed barrier. If pests are a concern, add a screen or mesh behind the frame.

Is it better than a fixed louver vent?

It closes in cold weather, which helps keep crawl space pipes warmer, and opens in warm weather to release moist air. A fixed vent stays open year-round and offers no control.

Does it run on electricity?

No. The coil is powered by temperature change alone, so there is nothing to wire and nothing to fail electrically.

How many vents does a crawl space need?

Building guidance generally calls for about 1 square foot of vent area per 150 square feet of crawl space, more without a vapor barrier. A 10-pack covers most single-family foundations.