Zone with Mixed Head Brands: First Heads Dry, Last Heads Drip

When a zone's first heads get no water but the last heads dribble, it's not a leak—it's a pressure/flow mismatch or valve restriction.

Immediate Check: Valve Flow Control

Locate the zone valve. Turn the flow control stem (top knob/screw) fully open (counterclockwise), then back off ½ turn. This ensures maximum diaphragm lift. If the stem was barely open, the valve acts like a restrictor—starving the first heads (highest friction loss) while residual pressure barely pushes water to the last heads.

If That Doesn't Work: Valve Internals

1. Shut off main water.
2. Remove valve bonnet (top half).
3. Inspect diaphragm for tears, debris, or deformation.
4. Check the valve seat and ports for pebbles, sand, or mineral buildup.
5. Clean thoroughly, reassemble, test.

Mixed Head Types Note

Nelson and Rain Bird heads have different pressure/flow curves. If the zone was designed for one type, mixing can cause uneven coverage—but it wouldn't cause zero flow at the first heads. Fix the valve first, then evaluate head performance.