Display shows dr or DR and heater is disabled, spa may not heat

Safety first: Turn off power at the breaker before loosening any unions or valves.

• Check water level: Ensure water level is above all skimmer openings and filter intakes. Low water can cause air ingestion and low flow.
• Clean or remove filters: Remove all filter cartridges and run the spa briefly. If the dr code clears and heat resumes, replace or deep-clean the filters.
• Bleed air from pumps: Loosen the pump unions slightly until water flows steadily, then retighten. This removes trapped air that can prevent priming.
• Verify pump operation: Run Pump 1 on low and high speed. Confirm strong flow from jets and through the heater return. If the pump hums but does not move water, the Master Spas jet pump may need replacement.
• Inspect slice valves and plumbing: Make sure all slice valves are fully open and there are no visible kinks or collapsed hoses.
• Reset system: After correcting flow, power cycle the spa. If dr persists with good flow, the flow detection circuit or pressure switch (if equipped) may be faulty and require professional service.