Hunter EC Controller Runs Pump in Reverse: Relay Wiring Fix

When a Hunter EC controller with a pump start relay runs the pump when off and stops it when a program starts, the relay is wired backwards—or the wrong relay type was installed.

Normal Relay Operation

A standard pump start relay is normally open. The controller sends 24VAC to the relay coil, closing the contacts to power the pump. When the controller stops, voltage drops, contacts open, pump stops.

Your Symptoms Indicate

• Relay contacts are normally closed (pump runs until controller energizes relay to open them), OR
• Control wires are swapped on the relay coil terminals.

Fixes to Try

1. Swap the two control wires on the relay coil (24VAC input). This reverses logic if wired backwards.
2. Verify relay type: You need a "normally open, energize-to-close" relay. The Iskra TRP-682 may be a "normally closed, energize-to-open" model—check the datasheet or contact Iskra.
3. Use a dedicated irrigation pump start relay (e.g., Rain Bird PSR, Hunter PSR, or K-Rail). These are designed for 24VAC controller signals and cost $30–$50.

Don't overcomplicate: a standard $40 irrigation pump start relay wired correctly solves this 99% of the time.