Ask 'Dr. Spa' Q & A Message Board

: Our spa is set to thermastat control and when the spa cover is off the
: temp stays constant as set. However, when the padded cover is on, the
: temp continues to raise over 6 degrees. Is this normal? Is there
: anything to be done to make it possible to have the temp ready to be
: used when the top is removed? Thanks
In the summertime or a warm climate, it could be "Normal" depending on what temp you are trying to maintain, ambient temps, how well the tub is insulated, and whether it sits in the sun or shade, but it sounds as though you have a thermostat problem. What brand and model is it? Does the heater continue to run, even after the water goes above the set temp? Have you tried setting the thermostat lower when the tub is not in use?

Until you check the thermostat out, try setting the thermostat down after you finish using the tub, and/or propping up one side of the cover with a tennis ball or the like to allow the excess heat to escape.