I have a classic brick chimney for a wood fireplace only (i.e. no hot water tank or other things sharing the stack).
In peak summer heat, the interior of the upstairs is well above the exterior temperature in the evenings for many hours.
I am wondering if a box fan pointing up the stack would be effective for pushing air out of the house.
It would be particularly convenient from a security point of view since the chimney is an existing hole in the structure, and "secure". We could even leave it running unattended 24×7.
Is this a bad idea? I'm OK if it's less efficient for some reason than a window or doorway placement. But if it would be completely ineffective, then, that would be a problem.
Best Answer
A cheap box fan will not push air through any enclosed structure like a chimney unless it is sealed into the opening so air will not just recirculate around the blade. Also, a fan used to move air through a duct or space must have a venturi built into the fans construction so that the air is displaced and does not just recirculate. To understand the fan's construction, search for whole house exhaust fans or exhaust fan venturi. The hole the fan blade sits in does not allow for air to recirculate back to the fans inlet just to be recirculated. Hope this helps.