Display shows dr or DR and spa will not heat; may show intermittent heating attempts

Safety first: Turn off power at the GFCI breaker. Do not continue to reset and run the spa with a dry heater; this can damage the heater tube.

Steps to resolve dr/DR:

• Verify water level: Fill the spa to the recommended level. Low water can cause the pump to draw air.
• Clean or remove filters: Remove the Strong Spas filters and clean thoroughly. Try running the spa briefly without filters to see if the error clears.
• Bleed the heater and pumps: Loosen the unions on both sides of the heater and on the circulation/jet pump until water flows steadily, then retighten. This removes trapped air from the heater tube.
• Check slice valves: Confirm that all gate/slice valves around the pump and heater are fully open. A partially closed valve can starve the heater of water.
• Inspect for leaks: Look for any leaks around the heater manifold that might indicate a cracked tube from previous dry firing.

When to call a technician: If dr persists and the heater shows signs of overheating (discoloration, warping, or leaks), the heater assembly may need replacement and the control pack should be checked.