Yeah I know this, and that's why I was hesitant to replace it. But I would argue that at over 9 years old (probably significantly more) my old igniter was probably quickly approaching the right side of that curve, and that's why I did want to replace it.For a large number of ignitors, or any piece of equipment, the failure rate follows the “bathtub curve” shown below, with a higher “infant mortality” rate at the beginning than later on in life. You have to make an estimate, based on the anticipated lifetime of an ignitor, where your unit is along that curve. I wouldn’t replace a piece of equipment that is operating normally and is critical to heating the house, just before going away.
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