As noted by one previous poster all materials in the attic must be plenum rated.
Attic furnace no return plenum.
Inspectors can learn how air leakage from ductwork may cause home energy loss increase utility bills lower comfort levels and make the hvac system less efficient.
Everything would need to be plenum rated including the low voltage cabling.
Ceiling space as a return air plenum.
The rating plate will state the max.
I think a cmp cable cost twice a non rated cable so my guess is all your communication fire alarm and misc.
Otherwise this is a code violation.
As long as there s an unobstructed path e g no door that can be closed the upstairs doesn t need a dedicated return.
An attic is a space not a structural component the space cannot support anything but air.
If there is no return duct the concept is that the attic space becomes a return air plenum and this is not uncommon in commercial plenums.
I used to work in house at a 40 story high rise.
The return air plenum was a room with doors and banks of filters.
Tesp is typically measured using a manometer and a dwyer 303 static pressure tip inserted into the return plenum just before the filter and in the supply hopefully before the coil then add the two numbers disregarding signs.
No radios or storage.
Not to mention that the air handler itself is in its own plenum.
If you have a door at the top or bottom of the stairs you can replace with a louvered door.
How can and attic be held to the same standard as a plenum when its used for storage and water heaters and such.
Anyhow the return box and the other box that has the ducts coming out of it are made of sheet metal.
The sealed attic is great with return and supply duct inside of the thermal envelope of the building.
You ll also need to provide a return path from a basement air handler or main level return to the second floor.
The return is on top and the supply is on the bottom.
Static pressure but it is usually 0 5 wci.
Cabling is not rated for plenum use.
If the space is conditioned it no longer is an attic and needs to be called conditioned space wiring within an area used as a plenum has to be in conduit.
A 14 trunk too small emerges from the foundation wall in the basement in a roughly 2 2 notch at the top of the foundation wall.
I have a huge concern about fire safety.
My mother has had me going up into her attic to seal the leaky ducts and parts of the plenum air handler that join up to the furnace and coil units.
Reality returns should be ducted with a small supply and return connected to the attic space.
No return air plenum.
