Display shows Sb; heater does not respond to normal temperature adjustments.

Safety First: Ensure safe access to the control panel; no need to open gas or water lines for this issue.

• Check mode setting: On the front panel, verify that the heater is not in "Standby" or "Service" mode. Switch to "Pool" or "Spa" mode as needed.
• Inspect external switches: Some installations include an external service switch. Ensure it is not left in service/off position.
• Configuration check: Refer to the Hayward manual to verify dip switch or menu settings for normal operation.