I looked at this heating unit today and had some questions. The home was built in the sixties and had some improvements done. My question is after you look at the pics of this, do you have any concerns? The two fent flues are one from the HVAC unit and one from the water heater. The water heater is the one up top. When looking at this unit (located in the finished basement) is when questions startedto pop up. There were three return air vents, two on the top floor (that did not appear to be working) and one in the basement right next to the furnace. It also seemed a little smallish(return air vent). What say you peeps?