For those of you that build or design homes I have a question. Why do you, or would you, locate a Heating and Air vent to supply air to a water closet? I mean you have a room with just a toilet in it and hopefully an exhaust fan, which I can see the need for, but then many place a Heating and Air vent right there in the same room, near the exhaust fan. I mean, naturally, the heating and air vents feed air into the room to be circulated back to the Heating and Air return thereby pulling whatever other air exist inside the water closet, sometimes not the most desirable air mind you, back into the other parts of the house where you wouldn't necessarily want that, less than desirable, air?
Is there some code or practice I'm not thinking of or is this just something someone hasn't really thought about? If there is no code to the contrary my choice is never to place an air source that will be sucked back to the return in a room for the purpose of a water closet. Same principal almost when you put a vent into a half bath that is located right off the kitchen and usually has no outside wall. Why the need for a Heating and Air vent there as that room is going to assume the temperature of the area around it which is already heated and cooled and thereby you eliminate the possibly that you will suck distasteful odors from the half bath through the kitchen on their way to the Central Heat and Air return.
Maybe it's much ado about nothing but I'm just curious about it.