Display shows dr or DR and heater shuts off; spa may not reach set temperature.

Safety first: Turn off power at the GFCI breaker. Do not allow the heater to run without confirmed water flow.

• Verify water level: Ensure the spa is filled to the proper level, above all suction fittings.
• Open all valves: In the equipment bay, confirm that all slice valves (gate valves) on either side of the pump and heater are fully pulled up/open. Partially closed valves can starve the heater of water.
• Bleed air from heater: Loosen the union on the heater inlet slightly until air escapes and water begins to flow, then retighten. Repeat on the outlet union if needed.
• Clean filters: Remove and rinse Marquis filter cartridges thoroughly. Try running the spa briefly without filters to see if the dr code clears.
• Check circulation pump: Confirm that the circulation pump is running and that there is strong water movement. A weak or failing pump can cause dry heater conditions.
• Power cycle: After purging air and restoring flow, turn the breaker back ON and monitor the spa through a full heating cycle.

If dr persists after ensuring proper water level, open valves, and good circulation, the heater element or control logic may be compromised and should be evaluated by a technician.