Is it normal to have a supply line run through a return (wall cavity)

[steppinthrax]

I was taking off my return register and notice the supply line that runs upstairs from the basement runs through the return to get there. This is is how the system had been set up since the house was built (1975). Also is it ok to have a wall cavity (space between joist) serve as a return to your furnace.

[lra]

wall cavities (internal) are commonly used for return air.

[lra]

having a supply run through the return is not common. Does it interfere with the return air ?

[town]

I was taking off my return register and notice the supply line that runs upstairs from the basement runs through the return to get there. This is is how the system had been set up since the house was built (1975). Also is it ok to have a wall cavity (space between joist) serve as a return to your furnace.

can you take picture?

[artman934]

by this do you mean you have an open return (as in no ductwork after the register) with the supply duct running through that space? if so, thats pretty common (commercial anyway)...

[AtticAce]

If the system works it is ok, just leave it alone and put the register back, go watch TV before it breaks.

[dan sw fl]

For A/C it should be OK and very rare.

For plumbing, I would say U have a problem.