Display shows dr or DR and spa shuts down heater with a low-flow or dry-fire warning

Safety first: Turn off power at the GFCI breaker. Running a heater without water can cause serious damage.

The dr/DR code indicates the control system believes the heater is running without adequate water.

• Verify water level: Confirm the spa is filled to the recommended level and that all jets and suctions are submerged.
• Open all valves: In the equipment bay, ensure all slice valves or ball valves on the suction and return lines, especially around the heater, are fully open.
• Bleed air from pump and heater: Loosen the unions on the circulation pump and heater slightly until water flows steadily, then retighten. This purges trapped air.
• Clean filter: Remove and rinse the filter cartridge. Try running the spa briefly without the filter to see if the dr code clears.
• Reset the spa: Restore power, then follow the control panel instructions to clear the error (often by pressing a specific button sequence). Observe whether normal flow and heating resume.

If dr persists and you cannot establish strong flow through the heater, the circulation pump may be failing or the heater may already be damaged. Have a professional inspect before further use.