Spa powers on but will not heat the water (no error code displayed)

Safety first: Unplug the spa before removing filters or opening any covers.

• Verify settings: Ensure the set temperature is higher than current water temperature and that any timer or sleep mode is disabled.
• Check cover usage: Always keep the insulated cover on while heating to reduce heat loss, especially in cool weather.
• Clean/replace filter: A clogged filter can reduce flow and cause the heater to cycle off. Clean or replace the filter cartridge.
• Monitor temperature rise: Measure water temperature over 4–6 hours. Bestway heaters typically raise temperature slowly (about 1–2°C per hour depending on conditions).

If there is little or no temperature increase despite correct settings and good flow, the heater element may be failing and the heater assembly should be tested and replaced by a technician.