Valve Manifold Upgrade: 1¼" to 1" Valves—Pressure Impact?

Old 1¼" HydroRain Valves → New 1" Manifold

6-zone system, 1.25 acre, farthest zone has 4 Maxi-Paws + 5 impact heads. Current 1¼" valves work; new manifold has 1" connections. 33% area reduction—will pressure drop at far heads?

Analysis

Maxi-Paws are low-flow (~3–5 GPM each). 4 heads ≈ 12–20 GPM. A 1" valve (Cv ≈ 20–25) can handle this with minimal pressure loss (<5 PSI at 20 GPM). The 20 ft move closer to source offsets friction loss.

Recommendation

Install the 1" manifold. It's standard, parts are available, and flow is adequate. If issues arise later, upsize the mainline from manifold to first head on problem zones.

Don't Overthink

1" valves are the industry standard for residential 6-zone systems. The reduction is negligible for your head types and counts.