I have a Laars LT heater (2006 vintage) that we only use a couple of times a month to heat the spa. A couple of weeks ago I noticed that, while heating, it was shutting off prematurely -- the first time when it reached 98 degrees, and the second time it reached the target 101 but wouldn't turn back on to reheat the water. The light was blinking so it was being asked to heat the water more, but wasn't coming back on and there were no trouble or service lights lit.
I noticed a lot of leaves under the exhaust grate, so I took that off after the last use and cleaned out the leaves hoping that was the problem.
Now, I noticed that the pressure switch light is lit. I had my pool guy (who cleans the pool and knows a bit about the equipment but doesn't do major repairs) look at the heater, and the cleaned out the pressure switch and put it back. Then I used the spa and it got to 100 before shutting off and refusing to come back on, again with no trouble lights.
We also cleaned the "flame sensor" and that was fine.
Now I see the pressure switch lamp is on again. Would it be worthwhile to replace the pressure switch, which looks easy to do as a quick fix? Or is this definitely a job for a pro?
Any tips for why it might not be coming back on? Is there some sensor that doesn't cause the trouble lights to come on?