Rain Bird 1800 Pop-Up Sprinklers Lose Adjustment Overnight

Thermal Expansion Affects Nozzle Setting

Two Rain Bird 1800 pop-up heads were adjusted for proper coverage, but reverted to dribbling by the next cycle. Swapping heads with ones from another zone moved the problem to the new location.

Root Cause

When the system is off, water in the pipes warms to soil temperature. The adjustment screw restricts flow through a very small orifice. Warm water expands the plastic slightly, closing the orifice further. The trapped warm water prevents cool water from reaching the nozzle.

Solution

Use a smaller nozzle or avoid turning the adjustment screw down too far. Rain Bird offers over 50 nozzles for the 1800 series; one will match the required radius without excessive restriction.