HydroRain Valve: Diaphragm or Ports? Diagnosing Low Pressure with Bleed Open

Troubleshooting a 1975 HydroRain Valve with Pressure Loss

An old HydroRain valve feeding an indexing valve shows low pressure when solenoid activates. Opening the manual bleed increases flow but water shoots out the bleed hole. Same with solenoid loosened. Water also comes from solenoid vent hole when loosened.

Normal Behavior: Bleed and Solenoid Vents Leak When Open

Water from the bleed screw and solenoid vent is normal when opened—they are atmospheric vents.

Likely Not the Diaphragm

A ruptured diaphragm usually causes weeping (slow leak when off), not pressure loss when on.

Check These Instead

1. Flow control adjustment – Open fully, close fully (count turns), open halfway.
2. Internal ports – Disassemble and clean all passages, especially the small port above the diaphragm.
3. Diaphragm condition – Replace if torn or deformed, but clean ports first.

If cleaning and adjustment don't restore pressure, replace the valve—parts for 1975 models are scarce.