Open the front skirt panel of the spa
Install two 1500 watts ceramic heaters pointing inward, do not use a heater with an element for this type will melt the plumbing
If available space permits it, close panels
If not, adjust side panels in an angle in order to create a wall. Place a tarp over the skirt side panels (created wall) and put spa cover back into place. Use central skirt panel as a back wall to create an enclosure to keep the produced heat circulating under the spa. Secure tarp in order to keep the heat inside enclosure.
Make sure all ventilation traps on your skirt are covered
Open the front skirt panel of the spa
Slide a 1500 watts ceramic heater inside, under the spa, do not use a heater with an element for this type will melt the plumbing
Put skirt panel back into place, should it stay ajar, add a tarp over the opening between the spa cover and the ground
Secure tarp in order to keep the heat inside
Make sure all ventilation traps on your skirt are covered
Open the motor compartment (spa step)
Slide a 1500 watts ceramic heater inside, do not use a heater with an element for this type will melt the plumbing
Put step back into place
cover rear ventilation trap in order to insure heat circulation inside the compartment