Has anyone ever blown a fuse that connects the control board to the loop pump? This caused a waterflow red indicator light and a low pressure indicator light and the system went into Aux mode. The system experienced a freeze condition when the thermistor detected the temperature drop due to no waterflow. I have had the system, a Waterfurnace Premier, for 8 years and never experienced any kind of issue before. My HVAC tech came out, traced the blown fuse, and replaced it. System has been heating fine since fixed a few weeks ago. I am curious what would have caused this? Do these fuses just wear out?
Heat causes fuse failure - either excess amperage or loosened connection. Fuses can weaken over time due to above reasons. Connections should always be checked and tightened when necessary. This is not an uncommon problem given the age of the unit.
