I want to put a toilet right where there is a heating duct under the
floor. Moving the heating duct is not an option because of cost and
the amount of labor required. This is the main furnace duct serving
the entire home. But I have an idea. Why not use that heating duct
for both supplying heated air, and toilet drainage. After all, a pipe
is a pipe. The toilet water will flow across the bottom of the duct,
and the air (being lighter), will flow in the top portion of the duct.
There's no reason this duct can't be used as dual purpose, since it's
Just before the duct enters the furnace, there is a main sewer line,
so if I install a baffle at that point, I can divert the toilet water
into the sewer and the upper portion of the duct will still serve as
the main heating duct for the home.
Not only will this solve the problem of the duct under the toilet, but
will save a large amount of money on that costly 4 inch sewer pipe.