Display shows dY or DY and spa will not heat properly after a refill

Safety first: Turn off power at the GFCI breaker before attempting to clear a dry heater condition.

dY/DY is a more serious dry-fire lockout that may require manual intervention.

• Inspect heater housing: Look for discoloration, warping, or burnt smell around the heater tube. If present, the heater may be damaged and should not be reused.
• Prime the system: Open pump and heater unions slightly to release trapped air until water flows, then retighten. Ensure all valves are open.
• Clean or replace filter: Remove the filter cartridge, rinse thoroughly, or install a new American Whirlpool filter if the old one is suspect.
• Reset control system: Restore power and follow the owner's manual procedure for clearing a dry heater lockout (often involves a specific button combination or power cycle).
• Monitor initial heat cycle: Allow the spa to heat while monitoring for unusual noises, smells, or error codes. If dY returns quickly, shut down and have the heater and control pack tested.

Because dry-fire can compromise heater integrity, replacement of the heater assembly is often recommended after repeated dY errors.