Attic Fan Ductwork

Jim asks is it ok to have a bath exhaust fan vent into my attic no it s never a good idea to have any exhaust fan in your home dump all that hot moist air in your attic.

Attic fan ductwork.

That condensation drips from the duct work in the attic space and the exhaust fan. Recently i had another hvac company come out and put in a new bathroom vent and they told me they believed the duct work was full of water. This is much easier to do if you have attic access because if you don t you usually have to remove some ceiling drywall and run the ducts along a joist. Meticulously seal seams and add reflective insulation around your ductwork convert your attic to a conditioned space.

Trying to solve the heat gain problem in your attic by using a fan is like lying out at the beach with a fan blowing over you and thinking you re not going to get a sunburn. It was new when the ac was put in 7 years ago. It can cause you a lot of problems with mold and mildew forming on the underside of your rafters and decking as well as getting into your insulation. Throw duct leakage into the mix and the problems are even worse.

The building code requires a bathroom exhaust fan to vent outside the building so installation of a new bathroom fan necessarily involves installation of ductwork. But while you can t have two fans with one vent you can make one fan and one vent serve two bathrooms. Using a fan to blow hot air out of the attic doesn t address the radiant heat flow from the roof to the attic floor. When bathroom exhaust ducts are not properly insulated and vented the warm moist air traveling through them hits the colder section of the duct in the unconditioned attic space causing condensation on the duct work.

The attic ductwork is flex duct work. In all cases the ducting needs to conduct the exhaust to the building exterior and needs to terminate in an animal proof vent cover. This american designed fan is designed to reduce attic temperatures and remove destructive moisture thus making your home more comfortable and reducing the load on your hvac system and lowering your electricity bills. With hundreds of square feet of ductwork surface area in the attic and a δt of 75 f the air coming out of the vents in your home will be significantly higher than 55 f.

In your attic it would be a good consideration to. Much of that heat then conducts downward and finds its way into the house. A grille in each bathroom attaches to ducts which then fasten to a y connector at the fan. Move the ducting and equipment to the crawlspace or the interior of your home.

This setup requires an in line centrifugal fan mounted in the attic drawing air simultaneously from both bathrooms see photo.