I have jacuzzi hot tub model h240000 z145/345. My heater will heat the water to about 108 degrees and then " OH " will flash into the display. No matter what temp. I have it set to it won't shut off until it reaches about 108 degrees and displays " OH " What can it be? Thanks for all responses.

OHOHOHOHOH just hope it doesn't get any warmer then OHOHOHOH l09 degrees. I suggest you call the people who installed the hot tub, or the manufacturer to get the problem solved before you get your but burned! :(

Most hot tubs are set to go no higher than 104, at you can set them higher. If yours is reaching a true 108 its likely the thermostat is not working. They usually are not repairable but can be replaced. I'd measure the temp with anothet thermometer before calling for servioce.