Display shows dr or DR and heater shuts down; may be followed by dY or DY.

Safety: Turn off power at the GFCI immediately to prevent heater damage.

• Check water level: Fill the spa so that water is above all jets and suction fittings.
• Open all valves: Verify that all slice valves or ball valves around the pump and heater are fully open.
• Bleed air from heater: Loosen the union on the heater inlet or outlet until water flows steadily and air stops escaping, then retighten.
• Inspect circulation pump: With power restored, listen for the circulation pump. If it hums but does not move water, it may be air-locked or seized. Turn power off again and manually bleed or replace the pump as needed.
• Reset error: After restoring proper water level and flow, power cycle the spa. If dr/dY does not return and heating resumes, monitor closely for normal operation.

Repeated dr errors indicate a persistent flow or pump issue. Continued operation can damage the heater; have a technician inspect the circulation system.