Safety first: Turn off power at the GFCI breaker. A dry heater can be damaged quickly if run without water.

Restore water and purge air:

Verify water level: Fill the spa to the recommended level. Ensure all suction fittings are submerged.
Clean or remove filter: Remove the filter cartridge and rinse thoroughly. Try running the spa briefly without the filter to see if the dr error clears.
Bleed air from heater and pump: Loosen unions on the pump and heater slightly until water seeps out, then retighten. This helps remove trapped air that can cause a dry condition.
Check pump operation: With power restored, confirm that the pump is moving water strongly through the jets and heater return. Listen for cavitation (gurgling) which indicates remaining air.
Inspect for leaks: Look around the heater and pump unions for leaks that could allow air into the system.
If dr persists: The heater may have been damaged or the control pack may be misreading flow. Have a spa technician test heater resistance and control board operation.

Display shows dr or DR and spa stops heating, may show after running for a short time

Possible Causes