Knowing that the issue traced back to the gas valve switch, and not wanting to tamper with gas pipes, I regretfully hired a professional to test and install the new gas valve switch. Surprisingly, the process was not as labor-intensive as I thought; it took them less than 30 minutes, and the burning of the fuse stopped. The whole series of clicks followed by the whooshing sound, which was a sound I had not achieved before, was a great feeling to hear. However, as we were finishing the repair, an unexpected issue arose: there was no heat, only cold air in the exhaust.
The repair guys took out the new igniter and performed a series of tests, only to find out that the new igniter was also not heating up. They ended up replacing my new controller, new wafer, and new ICM, reinstalling my old controller, wafer, and ICM. And voila, the heat soon filled the area where I was standing.
It was a first-world problem that had never been sweeter to fix, especially after the agonizing two-plus weeks of troubleshooting. Plus, my wife added pressure, making it even more challenging because, as she rightly pointed out, I made the bed, so I had to sleep in it. I paid those guys pretty much with a blank check, and at that time, it seemed fair and just. Then, I returned all the items that were not needed because the old ones were still functioning. In the end, I gained $50 back compared to how much I paid the repair guys. But kidding aside, the lesson that I learned throughout what I called the "heck week" was the knowledge that I gained.
I learned that Pentair originally manufactured high-altitude research balloons and not pool equipment, which I found interesting. I also learned about the components inside the heater; after opening the top lid almost a hundred times, my fingers developed their muscle memory of where wires, nuts, and bolts go. A community of like-minded individuals like you all made it less difficult to find the problem sooner rather than later. I know that at the end of the day, Tom Brady took it to the end zone (just an analogy), but I moved the ball across the field to help the process. I consider this mystery of the burning fuse case closed.