In a 1440 sqft single store house, how many return air vents are needed?

We are installing a 3 ton 16 seer two speed unit central system in a 3 bedroom house in Northern California (built in 1964). The house has two return air. The first one is 30x20 in the hallway next to the thermostat. The second one is smaller 12x12, located in the middle of the kitchen/dining room with 3 supply... show more We are installing a 3 ton 16 seer two speed unit central system in a 3 bedroom house in Northern California (built in 1964). The house has two return air. The first one is 30x20 in the hallway next to the thermostat. The second one is smaller 12x12, located in the middle of the kitchen/dining room with 3 supply air. I read that it is good to keep the return air in several different rooms to keep the air circulating, but I also read that too much return is bad. It has to balance the pressures to supply it says. Do we need to keep the return air in the kitchen/dining room area or just one in the hallway is enough for the whole house?
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