Ok, here is an interesting one for the forum.
I recently moved to a large house in the metro DC area, it has an unfinished basement of approximately 1500 square feet.
There is no return vent, and the HVAC units are both located in the basement.
I have relocated 60+ industrial rackmount servers to the basement, each of which has dual 600 watt power supplies. During standard operation, they each draw about 550 watts, 1.5A. I am using the extra gear in the basement for surplus computing capacity to our standard datacenter operations.
The house has two HVAC units; one for the second floor, and a 3 ton Trane XE90 for the basement and ground level.
There is no return air vent in the basement, just the ducts that feed the basement (three cool air vents) as well as the insulated ducts that feed the ground floor.
Near the three racks of computer equipment, I have added two additional cooling vents from the duct that blow cool air directly on the equipment. I do not however have a way to evacuate the heat from the basement, so I am thinking about adding a 20"x20" filtered vent on the heat intake directly on the HVAC heat intake duct itself.
So the questions are this - what is the minimum distance a cool air vent can be near an intake vent? Will adding a heat intake vent in the basement detract from the ground level intake to the point of the ground floor getting hot? Right now the ground floor is perfect temperature, but the basement is running 85+ degrees. I can either add an intake vent on the duct that feeds the HVAC unit itself, although that is withing a 5' distance to the two new cooling vents I added, or I can add another intake vent at the top of the stairs where the heat is really collecting via convection effect.
Any ideas on this?