Display shows dr or DR and heater is disabled; spa may attempt to heat and then shut down.

Safety first: Turn off power at the breaker. A dry-fired heater can be dangerously hot.

• Verify water level: Fill the spa so that water is above all skimmer and suction fittings.
• Open all valves: Ensure all slice valves around the pumps and heater are fully open and locked in place.
• Bleed air from heater: Loosen the unions on both sides of the heater tube slightly until water flows steadily, then retighten.
• Check circulation pump: Restore power and confirm that the circulation pump runs and you see flow at the heater return. If the pump hums but does not move water, it may be seized or air-locked.
• Inspect heater: If the heater housing is discolored or smells burnt, it may have been damaged by dry fire and should be replaced.