Posting the results for anyone lurking and reading. There was a knob plate behind the dial that has a screw in it that can be screwed in to keep the temperature from being turned up higher than you want it to. It's a way to lock the temperature so the kids or other people can't turn it up too high. I had googled and googled before I called the repair company and couldn't find the answer anywhere. It was in the manual and I missed it. I did feel pretty foolish. The repairman didn't charge me for the visit, but did tell me the heater was out of code, being closer than 4 feet to the house, though, and that he'd have to write up a disclaimer. He kept telling me he was afraid it would melt the siding on my house and that I shouldn't run it at all, and don't ever run it while I wasn't home. And that he was sure that was the reason the previous owners refused to open the pool for a pool inspection and offered a pool warranty add on to the home warranty instead. My husband and I decided not to use the heater anymore, and I was planning on emailing our agent to see if we had any recourse with the previous owners. After spending the evening planning a remodel of the backyard, trying to figure out where to move the pool, place the pump, move the deck, figure out IF we can move the deck, calculate how much to move the gas line, and where to put the heater so that it has the proper clearance, I reread the heater manual and found out it has the proper clearance after all. I had read the heater manual when we hooked it up, but it was easy to forget when the repairman said it was dangerous to run it. Remember to read the manual again before you call a repairman. LOL.