Anyone had a gable attic fan installed lately? If so; 1) What % did it reduce yur A/C bill from previous year 2) What was total cost? fan and installation? 3) Recommendations for installer? Thanks for any recommendations. July electricity bill blew our roof off! LOL
You'd have to tell us if you already have passive ventilation? If your house is less than 20 to 25 years old you have passive. (code requirement) If you do have passive, don't waste the money. It will cause more cost and problems than benefits. Assuming you have passive: Your attic space is at equal air pressure now. Adding a ventilation fan creates a negative pressure that will need to be equalized. It equalizes by sucking air from the point of least resistance. That means pulling conditioned air from every leak in the living space envelope. Leaks in the envelope can go as far as the crawl space. If you have any uphill air leaks between your shingle and the ply it's nailed to; it will suck water through there when it rains. During storms the pressure may change abruptly in the attic causing a higher differential in pressure and increase the fans negative effect. 1. Your money would be spent better by adding ceiling insulation to an R30 or higher value. Blown in and batt insulation have an R3.2 per inch of depth. Blown in will compress over time reducing it's R value. You can measure it to see what you have now. (ex. 6" insu = R19) 2. Check all the HVAC Ductwork, if it's in the attic, for lose joint tape and screws, lose duct insulation, ducts compressing the ceiling insulation, etc. Duct tape is a wonderful thing for those fixes!!:lol: 3. Check your passive ventilation at the eaves to remove any insulation that is blocking the vents. Installers get sloppy sometimes because they know your not crawling out there to check it. 4. Next time you need a new roof, pick the lightest color shingle. They don't heat up as much. Hope that helps.
Thanks for the informative post...an attic fan has been on my to-do list for years. Would it be safe to say that a passive attic vent system can (probably) be identified by the ridge vents? Going back to the OP's question -or at least part of it- assuming you have a non-passive vent design without a fan is it worth the $ to install a fan?
