This is our manifold installed on the ceiling in the laundry room. Cold water enters on the right (orange port), it's sent to all the blue ports and then out one of the orange ports on the left. After leaving the manifold, the cold water goes upstairs to the water heater and loops back down, entering the bottom orange port. Hot water is then distributed evenly through the red ports.
The gas system comes in and splits here. Normal gas systems have 0.5 PSI but we have a fairly high demand because of the water heater so we raised it to 2 PSI. The pressure is reduced near the points of use via in-line regulators, dropping the pressure back down to 0.5 PSI. Long runs of pipe cause pressure drop so this way the pressure remains high even when multiple fixtures are using gas at the same time.