I have an EasyPak Versiheat Electronic Control Pack on my spa and have experienced problems regulating the temperature. The problem is that I will have the tub set for 101 degrees and when I go to get in, sometimes it will be at 108 or higher. This happens about once every two weeks. I found that if I turn the main breaker off and back on, it resets, and after about 8 hours, it cools back down to 101. I checked the actual water temp with a remote thermometer and it agreed with the digital readout. I thought the heater relay may be sticking, so I had the whole circuit board bench tested. The tech found nothing wrong other than the relays were worn. He replaced three relays, sent it back to me and it appeared the problem was solved. After about 2 weeks of operation, to my dismay, the problem reoccurred. Now I have no clue what could be wrong. It seems to me that the problem could be a thermostat problem, but I don't have a thermostat that I can see. The only thing I haven't replaced is the pressure switch on top of the heater. I don't see how that could be connected to this problem. This is rapidly getting old. Any ideas?

Something wore out the relays. The heater element may be going bad or you might have a loose connection in between the board and the heater.