Electric Furnace have been around for many years using control components called sequencers to allow for a way to stage or delay the timing between the energizing of the electric elements.
A series of delays are required to have the blower fan start after the first element is energized and to progressively engage the other elements in “sequence”. Without the delays the fan would start off blowing cold air until the ductwork warms up, and the heat within the ductwork would get trapped and not be delivered unless the fan operation was also delayed during shut down.
Every time your Electric Furnace turns on and off these sequencers are being used over and over again. Sequencers have contacts that carry the full load of the heating element, typically 5000 watts. Although the contacts are sealed and not accessible for maintenance they will usually last between 3 to 6 years before they fail.
Much the same as the tires or spark plugs on a vehicle wearing out, it is a good idea to simply replace them all when one fails since they will be the same age and will have close to the same wear. This will save you service fees in the long run especially if you live in a rural community. Electric Furnace
Author: Mark Boissoneault