HVAC for our 1st flr is in basement (there is another unit in the attic for flrs 2 & 3). During a recent renovation the return for the 1st flr was removed to make way for a coat closet. To make-up for the that they added a return in my unfinished basement that connects directly to the air handler and separately cut a hole in the wall/stairway from the 1st flr that leads to basement (thats not connected to the air handler), added a grille to it and said thats your your return system. So I was left with no direct return on the 1st flr for the HVAC just the grille opening in the stairway that is suppose to feed the sytem air from the 1st flr in addition to it pulling strictly basement air. Does this sound ok? The issue was raised when a different contractor came out today to service my boiler. He wanted to know why there was no return for the HVAC on the 1 st flr and suggested I should definitely have my return on the 1st flr because the cut out in the stairway is not adequate which is starving the system of air and that I was only sucking in dank, much colder basement air which in the winter causes the system to work much harder to convert that air to heat.
Also worth noting that in the basement is also a boiler for my radiators and a gas water heater (after reading some posts here that may a whole a new problem? - against code and harmful combustion air)