We're new at this, and I have a quick question. We're putting in a small, home sprinkler system, and we have a manifold with 3 valves (1 zone for grass, 2 for gardens), and a box that's big enough for them to comfortably go in. We have the anti-siphon valve to go between the house line, and the manifold, but does it have to be in the same box as the manifold, or in a box at all? Our yard is really flat, so having it 6 inches above the sprinkler heads isn't hard. Is putting a box over the anti-si...