My cabin is made of block with a wood floor. It's about 20' x 25'. It has a fireplace. About 3 feet from the fireplace almost in the corner of the cabin is a floor vent about 12 inches square. You can open it and close it. I've owned the cabin over 5 years and am still not sure what the vent is for and should it be open or closed. I keep it closed all the time. Anyone have any ideas?
It's not a crawl space. The block goes down into the ground and the are 2 vents on the outside that are beneath the floor level to let air in under the floor. That makes sense about letting air in for the fireplace.