I recently replaced my water heater with a tankless model and now I have an old 4-inch exhaust pipe in my garage ceiling that ends about 3 feet above my attic floor. My attic gets super hot, often reaching 120°F now, and I expect it could hit 140°F in August. Considering my roof has both ridge vents and soffit vents, I'm thinking about installing a ducted fan at the top of this exhaust pipe to pull cooler air from the garage into the attic. I plan to set it on a timer for specific hours. It seems like it could help lower attic temperatures and prevent my AC ducts from overheating. However, this project will only cost me around $30. Am I overlooking any important factors?
3 Answers
If I were in Florida, I'd focus on passive ventilation as much as possible, and I would insulate any ducts up there like crazy. I doubt your fan idea will have much impact. It might not be enough to drop the temperature significantly, honestly.
Is your garage attached to your house? Just be careful where the makeup air will come from; for example, check if there are gaps around your door frame that might let conditioned air escape from your house.
Attic fans only really work if the attic ventilation is set up properly, and if it's well sealed. Otherwise, you'll just end up sucking conditioned air from your living space or pulling in a ton of dust and pollen. That's why many people don't install them much anymore; ridge and soffit ventilation usually does the trick without the issues.