In this troubleshooting situation we have a customer who reports that when they turned on their nine-year-old electric furnace at the beginning of the heating season, they considered that the run cycles may have been excessive. But they didn’t call for service since they though the house seemed to be warm by comparison to the performance they noted from the previous season.

Further into the heating season, however, they realized that the equipment was not performing due to constant operation and the fact that the temperature in the building never reaches a comfortable level.

When you arrive, you note that the unit, which is a heating only system, is operating with a clean filter, and the air flow in and out of the cabinet is sufficient. A check of the temperature differential between the return and supply air shows it to be significantly lower than it should be, which leads you to check the operation of the components in the unit, shown in the schematic in Figure One.

Using a voltmeter, you check at each of the three heating element connections, and get the following results:

….Bottom Element: 240 VAC, 0 Amps

….Top Element #1: 240 VAC, 0 Amps

….Top Element #2: 240 VAC, Manufacturer’s Rated Current Draw

Your two-part troubleshooting question:

  1. What do you need to do in order to get this equipment back on line?
  2. What would you consider to be a reasonable explanation as the sequence of component failure in this situation?

Compare your answer with ours HERE.

Publication date: 2/04/2019

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