Display shows dy or DY and spa shuts down heating cycle

Safety first: Turn off power at the GFCI breaker. Repeated dry firing can permanently damage the heater.

Steps to address dy/DY:

• Resolve any dr/FLO issues first: Follow the steps for dr and FLO to ensure proper water level, clean filters, and no air locks.
• Inspect circulation pump: With power briefly restored, verify that the circulation pump runs continuously when heating is called for. If it hums but does not move water, it may be seized.
• Check heater pressure/flow sensor: Some Strong Spas packs use a pressure switch instead of a flow switch. Inspect the switch and tubing for blockages or kinks.
• Replace failing components: If the circulation pump is weak or the pressure/flow switch is unreliable, replace with Strong Spas-compatible parts.

When to call a technician: If dy returns after component replacement, the control pack may be misreading conditions and should be professionally tested.