Open a window or turn on a fan to provide adequate ventilation.
Any reason for an open duct in an attic.
Ductwork in the attic is subject to heat or cooling loss.
In more cases than not a 3 ton ac with the ducts in the attic has a ton or so of load that s just from the location of the ducts in the attic and the associated duct gains leakage etc.
One reason that ac units go up in attics is because they re cheaper and easier to install.
Those are valid reasons to do it so the real answer is to make the attic at least semi conditioned space.
Ductwork of less than 40 feet in unconditioned areas such as an attic if.
I live in a 3 story townhouse and my return air ducts for the 3rd floor.
It helps prevent ice dams in winter by keeping your roof cooler.
Once something shunned and banished to crawl spaces and attics exposed ductwork is on the rise as a design element and as an energy efficient solution.
It s done this way because it s easier and cheaper to run a flex duct through a wide open space than to fit it through and around floor and wall framing.
I can t think of any reason not to run the duct through any open path.
If you have a soffit with ducts in it and there is a small duct leak due to imperfect mastic at a duct seam the entire soffit can become pressurized.
That saves time and whenever your contractor doesn t take as long to finish a project you save in labor too.
Venting an attic is essential for a number of reasons including.
If there are any tiny leaks in the home s thermal envelope for example rim joist leaks or ceiling leaks the pressurized soffit will assure that lots of air escapes through a small hole in the thermal envelope.
To reset the switch you ll need to climb up into the attic and push the button manually.
And on a vertical run between floors i like to have a fire block between the floors but that may not be code in a single family dwelling.
If the duct goes into any uninsulated space you ll need to have the duct itself insulated.
Naturally those considering vaulted ceilings or increasing headroom in their home will need to consider what s hidden above.
It prevents moisture buildup that can cause mildew and rot in the attic framing and sheathing.
It s a lot simpler for your installer to leave ductwork loose rather than having to cover it and wind it through floors and walls.
It also makes maintenance and or modification easier.
