Can basement air serve as the only return air source?
Especially so if the are gas appliances present -i.e. furnace, water heater and electric clothes dryer, fire place ash pit?
I would think this is some sort of bldg violation
The return has to exceed the output since pulling in air is more strain on the motor than pushing it out.
For the most part you can have the return anywhere you want to as long as it is in the heated envelope. You can't pull in outside air because it will pressurize your home and force out heated or cooled air. It's a lot cheaper to use already conditioned air for almost all cases.
If you want to have a return in the basement here are some things to consider.
You have to have a clear path from the upstairs to the intake. This would include an open door or floor registers. I don't like doors in the way of the flow because if someone closes it they your flow is restricted. Not good.
I use physics to help me cut my heating and cooling costs and improve air flow.
In the summer I have intakes on the basement that pulls in cooler air and moves it to the upstairs. In the winter I pull warm air in the attic bedroom down to the furnace.
I just flip a few baffles when the intake flow changes. I am now in the winter settings and pull the warm air from the attic.
The short answer is yes, you can use basement air.
My idea of a perfect day: No where to go and all day to get there.