Are attic followers definitely worth the expense? – Orange County Register
Q. I would love to hear your thoughts on attic fans. Is it worth installing or just wasting your time and money?
A. I’m not a huge fan of attic fans. These fans are usually mounted in the top pitch of the roof and are used to cool the attic, save energy on cooling costs and extend the life of the roof shingles. The thermostat-controlled fans work by forcing out the “upper” hot attic air and drawing in cooler outside air, usually through the lower soffit openings.
The unmentioned evil of these fans is that they often draw air-conditioned indoor air from the lower floors into the attic through small cracks in the ceiling and other leakage areas (wires, pipes and similar ducts). As soon as this happens, the negative pressure created in the house draws in hot outside air, which means that the air conditioning system works longer.
I’ve also heard that attic fans on gas appliances (e.g. water heaters) can cause backflow issues that can lead to health and safety issues. The fan basically causes air to flow through the vents rather than the passive roof vents, which causes a water heater or boiler to not properly vent its exhaust gases and the fumes actually get into the house. I would consult your plumber or HVAC technician on this matter.
Because of the negative pressure in the house that these fans create, I don’t think they’ll save you money on electricity or cooling bills.
Let’s say you have a super-tight house and no leakage. There are solar powered fans on the market that do not use electricity. These fans won’t cost you anything to run, but you still have the negative pressure problem. Additionally, it will take you a decade or more to cover the cost of buying and installing an energy saver. I would only consider a solar powered fan if you were new to spinning and already had a reason to be on the roof.
If you are uncovered and have gas appliances prone to backwater, I recommend allowing passive ventilation through natural convection (upward heat flow through soffit, eaves, and ridge vent).