Valve Manifold Checklist

Manifolds get built once and serviced for twenty years. Every shortcut at assembly — no unions, jammed valve boxes, unlabeled wire — is paid for by whoever kneels in that box in an August service call. This checklist is written for that future technician, who is often you.

Layout and placement

1. Group valves in manifolds of 2 to 4 near the zones they feed rather than one mega-manifold at the house — shorter lateral runs, less pressure loss, easier diagnosis.
2. Place boxes in beds, not turf, clear of mower paths, with the box lid flush to finish grade and accessible after plants mature. Not under the future hedge.
3. Set the manifold 10 to 12 inches deep so the box lid closes over the valves with working room around each solenoid and bonnet.
4. Maintain backflow protection upstream per city code (most North Texas cities require a testable double-check or PVB with annual test) — never tee ahead of it.

Assembly

1. Build the manifold from schedule 40 fittings; flush the mainline thoroughly before installing valves so construction debris never reaches the diaphragms.
2. Install a union on the downstream side of every valve (upstream too on premium work). A ten-dollar union turns a valve replacement from a glue-and-wait job into a fifteen-minute swap.
3. Confirm flow-direction arrows on every valve body before gluing. Reversed valves weep and hammer.
4. Keep 2 to 3 inches between valves for hand and wrench clearance.
5. Bed the box on 3 to 4 inches of gravel with fabric under it — drainage keeps solenoids and wire splices out of standing water, and the fabric keeps clay from swallowing the gravel.
6. Support pipe so no fitting carries soil load; backfill around (not just over) the assembly and compact lightly.

Wiring

• Use direct-burial irrigation wire, 14 AWG for typical runs (18 AWG multi-strand acceptable on short residential runs — check controller spec and distance charts).
• Every splice gets a waterproof gel-filled connector, made inside the valve box, never buried in open soil.
• Pull at least two spare conductors to every manifold. The spare wire you pull today is the trench you do not dig in three years.
• Leave an 18 to 24 inch service loop of wire coiled in each box.
• Standardize wire colors (common is white — always) and record the color-to-zone mapping.

Test, label, document

1. Pressurize the mainline and inspect every joint dry before backfilling the manifold trench — a mainline leak found after backfill costs ten times more.
2. Activate each zone from the controller (not just the bleed screw) to confirm solenoid wiring, then walk the zone while it runs.
3. Label each valve with zone number and coverage (e.g., Z3 — front turf east) on a tag zip-tied to the solenoid wire, and mark the box lid.
4. Photograph each open box before closing, and record GPS or triangulated measurements for buried boxes on the as-built.
5. Leave the as-built zone map and wire color key in the controller door and in the closeout email.

Budget the extra fittings into the bid, not around it. A union and a spare conductor on every valve adds a few dollars of material per zone against a service call that runs an hour of drive and labor five years from now. On a six-zone system that is a handful of unions and one extra reel of wire — cheap insurance that a homeowner or property manager never notices until the day it saves them a full mainline dig to find a bad splice buried without a box.