Control displays 'RAY' and heater will not fire or respond to thermostat calls.

Safety first: Turn off power to the heater at the service disconnect and shut off the gas supply before opening any panels. Pool heaters contain live 120/240V circuits and gas components.

Steps to check when 'RAY' is displayed and heater will not fire:

• Verify call for heat: Ensure the pool/spa thermostat or automation system is actually calling for heat. Raise the set temperature 5–10°F above current water temperature.
• Check mode selection: On models with POOL/SPA selector, confirm the correct mode is selected and not in OFF or STANDBY.
• Inspect external controls: If using an external controller (automation), verify the 2‑wire or 3‑wire connection to the Raypak control board is secure and not corroded. Bypass the automation by switching the heater to STANDALONE or disconnecting the remote terminals per the manual.
• Check water temperature sensor: If the sensor is reading water temperature equal to or above setpoint, the heater will remain in standby and only show 'RAY'. Lower the setpoint then raise it again to force a call for heat.
• Measure control voltage: With power ON (only if you are qualified), verify 24 VAC between the control board R and C terminals. Low or missing voltage indicates a transformer or wiring issue.
• If no call for heat is recognized: With power OFF, inspect the thermostat/temperature control wiring harness to the main control board for damage or loose connectors. Reseat all plugs.

When to stop: If you are not comfortable working around live 24V circuits or cannot identify why the board is not recognizing a call for heat, contact a qualified pool heater technician.