Regarding your statement
"They close with the rain, but we have not been able to get them to reopen. for this reason we put vent covers on 2 of them. We will definately have them checked at the Frog Rally in August."
In a phone call directly with Fan-Tastic directly (800-521-0298) I discussed the features of the model 7350 and it's operations.
Fan-Tastic Vent's Retail 12 Volt Fans
1. They mentioned the units once upon a time had circuitry that re-opened the vent after the sensor dried, but it became a problem more often that not, so they discontinued the feature. Note the feature description above.....no mention of auto-open after drying.
To others in this discussion...............
With respect to vent covers, see this from their FAQ page:
Q DO YOU RECOMMEND VENT COVERS?
A Fan-Tastic Vent recommends using only UltraBreeze Vent Covers for your Fan-Tastic Vent. UltraBreeze Vent
Covers allow up to 100% airflow. The use of other vent covers greatly restricts airflow (by up to 75%), causing accumulation of dust and increased sound levels.
I always have vent covers over my fans but there are different brands out there!