The water temperature rises 2-3ºF (1-1.5 ºC) per hour. As with any large volume of water, it will take time to heat it up. Be aware that the initial heating after filling may take as long as 20 hours to reach the maximum temperatures depending on the starting temperature of your fill-water and external conditions. The following condition will lead to slow water heating:
- The ambient temperature is lower than 50ºF (10ºC).
- Outdoor wind speed is above 8-12 mph (3.5-5.4 m/s).
- The air bubble function is activated when heating the spa water.
- The spa is not properly covered with the spa cover when the water is heating.