Guy's how long have you been crawling under houses? ever wonder why some are wet and some are dry? auto vents are the type that surround a crawl space. They have a thermostat that opens and closes the vent according to temp. It allows warm air to circulate but when it gets cold they close. I usually combine these w/ plastic on the groung under the house. You tell the customer it will keep there floors warmer and the underside dryer. Good easy money.
This is CABL.com posting #287794. Tiny Link: cabl.co/mbm10