Spa heats very slowly and struggles to reach set temperature, especially in mild weather.

Safety first: Disconnect power before inspecting heater or insulation.

• Check cover and insulation:
  • Ensure the Avenli spa cover fits tightly with no large gaps.
  • Add an insulating ground mat under the spa if not already present.
• Clean or replace filter:
  • A dirty filter cartridge can reduce flow and heater efficiency.
• Descale heater (if accessible):
  • In hard water areas, scale can build up inside the heater tube.
  • If the heater can be removed, soak in a manufacturer-approved descaling solution, then rinse thoroughly before reinstallation.
• Verify temperature reading:
  • Compare displayed temperature with a separate waterproof thermometer in the spa.
  • If readings differ significantly, replace the water temperature sensor.